Subtract Fractions and Mixed Numbers with Unlike Denominators

We can use fraction models to subtract two fractions

To subtract the fractions with unlike denominators, rename them as the fractions with a like denominator. For example, to subtract 3/8 from 2/4, 2/4 can be written as 4/8 and then find 4/8 – 3/8

To subtract mixed numbers with unlike denominators, first we need to rename them as mixed numbers with a common denominator and then find the difference

To rename mixed numbers as mixed numbers with a common denominator, rename the fraction parts using LCD

The Least Common Denominator (LCD) is the Least Common Multiple (LCM) of the denominators

Sometimes, after renaming mixed numbers with like denominators, we need to rename to simplify the difference. For example, 3 1/2 – 1 3/4 = 3 2/4 – 1 3/4 = 2 6/4 – 1 3/4