Just as you would simplify any other fraction:
Step #1:
Find the greatest common factor of the numerator and denominator.
The factors of 32 are 1, 2, 4, 8,16, and 32.
The factors of 4 are 1, 2, and 4.
The common factors are 1, 2, and 4.
The greatest one is 4.
Step #2:
Divide the numerator and denominator by their greatest common factor.
(32 / 4) divided by (4 / 4) =
8 divided by 1 =
8 . <=== the simplified form of the fraction you gave us.
