1. 4x-12=18-x
4x-12-18+x=0
5x-20=0
x=-4
2.4*x-9*(x-7) = -12
4*x-9*x+9*7 = -12
63 - 5*x = -12
-5*x = -75
x = 15
с чем смогла,с тем
