Subtracting Fractions with Unlike Denominators and finding LCM

Subtracting fractions with unlike denominators means finding the difference between fractions that do not have the same denominator. Before subtracting, students must find a common denominator so the fractions are divided into equal-sized parts. Then subtract the numerators while keeping the denominator the same.

A common mistake students make is subtracting the denominators along with the numerators. Another mistake is forgetting to change both fractions to equivalent fractions before subtracting.