How do i solve this problem of factoring trinomials

Subtract 12 on both sides
n^2 + 4n - 12 = 0
factor the -12
to find numbers that add to make 4.
-12 = 6 * -2
6 + -2 = 4

(x + 6)(x - 2) = 0

then x = -6 or 2