а) (2х + 4) (3х - 1) - (6x - 12) (х + 3) = 100;
6x²-2x+12x-4-(6x²+18x-12x-36)=100
6x²+10x-4-6x²-18x+12x+36=100
4x=100-32
4x=68
x=68/4
x=17
