MENINGATKAN KEMAMPUAN PEMECAHAN MASALAH MATEMATIS MELALUI MODEL PROBLEM BASED LEARNING: IMPROVING MATHEMATICAL PROBLEM SOLVING ABILITY THROUGH THE PROBLEM BASED LEARNING MODEL. (2020). Abacus: Academic Journal of Mathematics Learning and Education, 1(1), 25-37. https://doi.org/10.59605/abacus.v1i1.383