(x - 2)(x + 4) - (x - 5)(x + 6) = x^2 + 4x - 2x - 8 - (x^2 + 6x - 5x - 30) = x^2 + 4x - 2x - 8 - x^2 - 6x + 5x + 30 = x^2 - x^2 + 4x - 2x - 6x + 5x - 8 + 30 = x + 22;
x = -2;
-2 + 22 = 20.
(x - 2)(x + 4) - (x - 5)(x + 6) = x^2 + 4x - 2x - 8 - (x^2 + 6x - 5x - 30) = x^2 + 4x - 2x - 8 - x^2 - 6x + 5x + 30 = x^2 - x^2 + 4x - 2x - 6x + 5x - 8 + 30 = x + 22;
x = -2;
-2 + 22 = 20.