Problem: 6 1/4 = z + 1 5/8
What is z?
6 1/4 = z + 1 5/8 = 6 1/4
Convention puts the variable on the left side.
z + 1 5/8 = 6 1/4
z + 1 5/8 - 1 5/8 = 6 1/4 - 1 5/8
z = 6 1/4 - 1 5/8
Adding or subtracting fractions requires that
they have a common denominator.
z = 6 2/8 - 1 5/8
"Borrow" 8/8 from the 6.
z = 5 10/8 - 1 5/8
z = 4 5/8 5 - 1 = 4; 10/8 - 5/8 = 5/8
Check it.
6 1/4 = z + 1 5/8
6 1/4 = 4 5/8 + 1 5/8
6 1/4 = 5 10/8 10/8 = 1 2/8
6 1/4 = 6 2/8
6 1/4 = 6 1/4
Answer: z = 4 5/8