This document discusses subtracting similar fractions. It states that to subtract similar fractions, you subtract the numerators and copy the denominator, reducing the fraction to its lowest terms if possible. It provides examples of subtracting fractions like 5/8 - 1/8 = 1/2 and 9/15 - 3/15 = 2/5, along with exercises to subtract fractions and reduce the results to their lowest forms.