i'm not to sure what this falls under but i don't understand how to multiply these
#1
(3x-12)(x-4)
#2
(6x-4)(3x+2)
#3
(2x^4 x^8 z^-6)(-3x^-3 y z^9)
#4
-12x^9 y z^10 / 3x^-1