Divide x2 - x - 12 by x - 4?

(x^2 - x - 12) = (x^2 - 4x + 3x -12) = x(x -4) + 3(x -4) = (x-3) x (x-4)

Hence (x^2 - x - 12) divided by (x -4) is (x-3)