This math topic focuses on practicing the subtraction of fractions by finding the lowest common denominator. Specifically, students are expected to determine an appropriate common denominator that would allow the subtraction of two given fractions with different denominators. Each question provides a pair of fractions and multiple choice answers for the lowest common denominator. Skills developed include identifying the least common multiple (LCM) of denominators and applying this in the context of fraction operations. This is part of an introductory unit on mixed fraction addition and subtraction.