4-n = 32

Write 4 as 22 and 32 as 25

(22)-n = 25

Multiply the exponents on the left to remove the
parentheses:

2-2n = 25

Since the bases on both sides are the same, and 
are different from 1, the exponents must be
equal also, so we set them equal:

-2n = 5

  n = -5/2

Edwin