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This quantitative study examines the influence of information quality, work engagement, and leadership style on decision making effectiveness among employees of a manufacturing company. Data were collected from 100 respondents using accidental sampling technique. Multiple linear regression analysis revealed that all three independent variables simultaneously affect decision making effectiveness. Partially, information quality, work engagement, and leadership style each have significant positive effects on decision making effectiveness. Leadership style demonstrates the strongest influence, followed by information quality and work engagement. The regression equation indicates positive contributions from all predictors. The coefficient of determination shows that the three predictors collectively explain a substantial portion of variance in decision making effectiveness. Findings suggest manufacturing companies should prioritize transformational leadership development programs, conduct information system audits, and implement work engagement initiatives to enhance decision making effectiveness. Future research should expand to other industries, add organizational culture variables, and employ longitudinal designs.

Sea transportation plays a crucial role in supporting national development, particularly in transporting goods and passengers. Tanjung Emas Port in Semarang, as a major port with high traffic, faces significant challenges in ensuring navigational safety. This study aims to analyze the partial effects of three key operational factors—Communication System (X1), Safety Facilities (X2), and Crew Competence (X3)—on Navigational Safety (Y). A quantitative approach was used with a sample of 100 ship crew members, selected using incidental sampling. Data were analyzed through descriptive statistics and Multiple Linear Regression (MLR) using SPSS. The results indicate that all three independent variables have a positive and significant effect on navigational safety. The regression equation obtained, Y = -1.398 + 0.218X1 + 0.278X2 + 0.302X3 + μ, shows that Crew Competence (X3) is the most dominant variable in predicting navigational safety outcomes. Collectively, these variables explain 72.4% of the variance in navigational safety. These findings emphasize that human competence and adherence to procedural discipline are critical leverage points in improving safety performance at ports.

This study aims to describe students’ mathematical problem-solving abilities on the topic of Systems of Linear Equations in Two Variables (SPLDV) based on Polya’s problem-solving stages in relation to their levels of self-efficacy. The research employed a descriptive qualitative approach with three ninth-grade students from SMP Negeri 5 Gresik in the 2024/2025 academic year, selected through purposive sampling to represent high, medium, and low levels of self-efficacy. Data were collected using a self-efficacy questionnaire, problem-solving tests consisting of two contextual essay items on SPLDV, and semi-structured interviews. Data analysis followed the interactive model of Miles, Huberman, and Saldana, encompassing data reduction, display, and conclusion drawing, referring to Polya’s four stages: understanding the problem, devising a plan, carrying out the plan, and looking back. The results revealed that students with high self-efficacy were able to complete all four stages comprehensively and reflectively, demonstrating systematic and accurate reasoning. Students with medium self-efficacy successfully performed the first three stages but failed to verify their final results, while students with low self-efficacy only reached the stage of understanding the problem and struggled to plan or execute solutions. In conclusion, the level of self-efficacy influences students’ mathematical problem-solving performance, particularly in terms of strategic accuracy, procedural precision, and reflective evaluation.

This study aims to analyze junior high school students’ mathematical reasoning abilities in terms of their levels of learning independence. The research employed a descriptive qualitative approach involving three ninth-grade students from UPT SMP Negeri 5 Gresik, each representing high, medium, and low levels of learning independence. Data were collected through a self-regulated learning questionnaire, a mathematical reasoning test based on the topic of Systems of Linear Equations in Two Variables (SPLDV), and semi-structured interviews. Data analysis followed Miles and Huberman’s interactive model, consisting of data reduction, data display, and conclusion drawing. The results revealed that students with high learning independence demonstrated strong reasoning skills across all seven indicators of mathematical reasoning (representing statements, making conjectures, performing manipulations, constructing proofs, drawing conclusions, verifying arguments, and identifying patterns). Students with medium learning independence fulfilled only some indicators, while those with low learning independence could only make simple conjectures without systematic reasoning. These findings highlight that learning independence plays a crucial role in developing mathematical reasoning, as it enables students to regulate their thinking processes, evaluate solutions, and correct errors. Teachers are encouraged to integrate learning strategies that foster self-regulation—such as the CORE and Flipped Classroom models—to enhance students’ mathematical reasoning skills.

This study aims to describe the understanding of high school students in solving high, medium, and low category HOTS (Higher Order Thinking Skills) problems and to explore the students' responses in solving problems related to the material of SPLTV (System of Linear Equations with Three Variables). This research is qualitative in nature, using a descriptive method. The subject selection technique used purposive sampling, involving three students from class X IPA/IPS SMAIT Nurul Fajri, with a total of 19 students. The data collection techniques included written tests on mathematical concept understanding using HOTS, interviews, and documentation. Based on the research results, it was found that the students' understanding of mathematical concepts in solving HOTS problems varied. The subject NF-17, with high ability, was able to answer well, including restating the concepts studied in problems 1, 2, and 4, classifying objects based on concepts, applying concepts algorithmically, relating various mathematical concepts internally or externally, providing examples or counterexamples, and presenting concepts in various representations in problems 1, 3, and 4. The subject NF-18, with medium ability, showed more limited results. Although able to restate concepts in problem 4, this subject could only classify objects based on concepts and apply concepts algorithmically in problems 1 and 4. This subject could only provide examples or counterexamples in problem 1. The subject NF-10, with low ability, was only able to restate concepts studied in problem 1 and did not show more in-depth understanding in other problems. These findings indicate variations in students' understanding of mathematical concepts in the SPLTV material.

This study aims to (1) describe the characteristics of e-LKPD based on realistic mathematics education on system of linear equations with three variables oriented towards critical thinking skills and self-efficacy of vocational school students, (2) describe the feasibility of e-LKPD based on realistic mathematics education on system of linear equations with three variables oriented towards critical thinking skills and self-efficacy of vocational school students in terms of validity,  practicality and effectiveness. This type of research is research and development (Research and Development) with the ADDIE model (Analysis, Design, Development, Implementation, Evaluation). The research subjects were 34 students of class X TKP SMKN 2 Tarakan. In this research, One Group Pretest - Posttest Design was used. The research instruments used were validation sheets, practicality assessment sheets by teachers and students, learning implementation observation sheets, critical thinking ability tests and self-efficacy questionnaires. The results of the research show: (1) the e-LKPD developed contains characteristics found in the RME approach to the material of on system of linear equations with three variables oriented towards critical thinking skills and self-efficacy. The characteristics contained in RME-based e-LKPD include integrated learning, use of context, mathematization and construction processes and interactivity. (2) the RME-based e-LKPD developed meets the criteria for feasibility in terms of validity aspects with a percentage of feasibility according to material experts of 93.4% and media experts of 98.9% with the validation result criteria being very feasible; practicality with a very practical category based on the results of student and teacher responses; effectiveness based on critical thinking skills with classical completeness of students reaching 82.4%, the results of the T-test paired samples-test with a significance level of 5% obtained that there was an influence on students' critical thinking skills after treatment using RME-based e-LKPD, the N-Gain result was 0.73 with a high category, and the effectiveness of e-LKPD on self-efficacy with an increase in each self-efficacy indicator,  the N-Gain result was 0.3 in the moderate category, and the results of the Wilcoxon test on self-efficacy data with a significance level of 5%, it was obtained that there was an influence on students' self-efficacy after treatment using RME-based e-LKPD.

This research uses the Polya problem-solving procedure to describe students' difficulty in problem-solving in the material about systems of linear equations in two variables. The method in this research is descriptive research. The subjects in this research were three students in Class VIII of SMP Negeri 6 Tondano. The data analysis techniques used are data presentation, data reduction and conclusion. The results of this research show that of the four stages of Polya problem solving, students who have the highest scores can fulfil all stages of Polya problem solving, students who have medium scores can fulfil three stages of Polya problem solving, and students who have high scores can fulfil two stages of Polya problem-solving.

Abstract: Indonesia, which consists of thousands of islands, reaching 17,001 islands, is known as a maritime country because the ocean area is larger than the land area, around 2/3 of the total area of ​​Indonesia. Sea transportation as part of the National Transportation System needs to unite all regions of Indonesia. Maritime transportation accidents occur due to 3 (three) important factors, namely human error, technical factors and weather (natural) factors. The purpose of this research is to analyze the influence between the independent variables, namely the Role of Harbor Master, Communication Ability and ISM Code, for the dependent variable, namely Shipping Safety. The population in this study was 130 people consisting of ship crew and employees of the PT. ASDP Indonesia Ferry (Persero) Padang Bai Branch who had knowledge classification about shipping safety and the sample in this study was 100 respondents with the technique used was non-probability sampling technique namely by using quota sampling. The analytical method used is descriptive analysis and quantitative analysis, data is analyzed using multiple linear regression analysis with the help of the Statistical Package For Social Science (SPSS) software. The results of this research by testing the t-test hypothesis show that the variables Role of Harbormaster, Communication Ability and ISM Code have a positive and significant effect on shipping safety at the Padang Bai Bali Ferry Port. Based on the results of the research, it can be seen that the research model of the multiple linear regression equation is Y = 2.898 + 0.436X1 + 0.214X2 + 0.189X3 + µ. From the regression results, it can be seen that the variable that has the most dominant influence on shipping safety is the role of the harbor master variable with a regression coefficient of 0.436. With the r square test of 0.526 or 52.6%, which means that the increase in shipping safety at the Padang Bai Bali Ferry Port is influenced by the Role of the Harbor Master, Communication Ability and ISM Code, namely 52.6% and other factors that influence the increase in shipping safety at the Padang Ferry Port Bai Bali was 47.4%.

This study aims to obtain teaching materials based on a valid, practical, and effective realistic mathematical approach, so as to improve students' mathematical reasoning abilities on the material of a three-variable linear equation system. The research instruments used were questionnaire validation sheets, lesson plans validation sheets, teaching material validation sheets, test instrument validation sheets, mathematical reasoning ability tests, and teacher and student response questionnaires to teaching materials. After all instruments, lesson plans, and teaching materials were declared valid by the validator, then readability tests and field trials were carried out. The results showed that: (1) the teaching materials based on the realistic mathematical approach developed had met the criteria of validity based on the validator's assessment with the average validity of the teaching materials for the material being 3.13 and 3.29 for media with a very feasible category; (2) the teaching materials based on the realistic mathematical approach that have been developed have met the practicality criteria through: a) the results of the questionnaire student responses to teaching materials show the percentage of practicality of 81.19% with a very practical category, b) the results of the questionnaire responses of teachers to teaching materials show the percentage of practicality 88.75% with very practical category; (3) The teaching materials based on the realistic mathematics approach developed meet the effective criteria with: a) classical student learning mastery of 88%, b) more than 65% of students have achieved 75% of learning objectives for each indicator, c) increased mathematical reasoning ability students after using teaching materials seen through the average score of students increased from 50 in the pretest to 85.33 in the posttest and the results of the N-Gain analysis which showed students' mathematical problem solving abilities increased by 0.712, meaning in the high category.

Traffic safety is influenced by several factors including Driver Discipline, Law Enforcement, Motorcycle and Road Conditions. Of the three, have an important role in improving traffic safety with satisfactory results. The purpose of this study was to determine whether or not there is an effect of Driver Discipline, Law Enforcement, Motorcycle and Road Conditions on Traffic Safety on Jl. Holy-Pati Raya In this study, the research population is Traffic Safety on Jl. Raya Kudus-Pati with a sampling system with a total of 100 respondents (sample). The variables in this study consist of: the independent variable is Driver Discipline (X.1), Law Enforcement (X.2), and Motorcycle and Road Conditions (X.3) and the dependent variable is Traffic Safety (Y). The research model is multiple linear regression analysis. The results of the analysis with statistical tools SPSS V.16 program obtained multiple linear regression equation Y = 2.758 + 1.963 X1 + 0.171 X2 + 0.287 X3+ µ . The results of the multiple linear equations show that there is a positive and significant influence between Driver Discipline on Traffic Safety (t count 13.675> t table 1.98447), Law Enforcement on Traffic Safety (t count 1.292 > t table 1.98447), Motor and Road Conditions on Traffic Safety (t count 2.099 > t table 1.98447), individually, Rider Discipline, Law Enforcement, Motorcycle and Road Conditions affect Traffic Safety. The influence of the three research variables is very strong with the coefficient value (R Square) obtained by 71% on Traffic Safety and 29% is influenced by variables that are not detected in this study.