x^2-4x-32 / x^2-20x-96

how do you simplify this?

If you meant:

(x^2-4x-32) / (x^2-20x+96)
then
= (x-8)(x+4)/((x-8)(x-12))
= (x+4)/(x-12) , x ≠ 8

If it is the way you typed it, .... what a mess that would become