Bonjour,
-7y+5(3y-6)-(6-8y) = -7y+15y-30-6+8y
= 16y-36
(3x+2)(-5x-7)-(x+6)(3x+2) = (3x+2)[(-5x-7)-(x+6)]
= (3x+2)(-6x-13)
= -(3x+2)(6x+13)