Abbas, Nurhayati, Nancy Katili, and Dwi Hardianty Djoyosuroto. “Teaching Materials of Problem-Based Linear Equation System With Two-Variables for Eighth-Grade Students in Junior High School”. Journal of Learning and Development Studies 1, no. 1 (December 31, 2021): 119–123. Accessed October 3, 2025. https://al-kindipublishers.org/index.php/jlds/article/view/2522.