Subtracting Mixed Numbers with Unlike Denominators

Subtracting mixed numbers with unlike denominators means finding the difference between two mixed numbers that do not have the same denominator. First, find a common denominator so the fractions can be compared equally. Then subtract the whole numbers and the fractions. If the top fraction is smaller than the bottom fraction, regroup or borrow 1 whole from the whole number.

A common mistake students make is forgetting to regroup before subtracting the fractions or not changing both fractions to equivalent fractions with the same denominator.