Answer :
6 1/4 = z + 1 5/8
6 1/4 - 1 5/8 = z + 1 5/8 - 1 5/8 Isolate variable
6 2/8 - 1 5/8 = z Least common denominator
4 5/8 = z Simplify
6 1/4 - 1 5/8 = z + 1 5/8 - 1 5/8 Isolate variable
6 2/8 - 1 5/8 = z Least common denominator
4 5/8 = z Simplify