2(3-x)-(6-x)
-1(3-x)-(12-y)
-(7-x)+4(x-5)
-9(y-4)-(12+y)

6-2х-6+x-3+x-12+y-7+x+4x-5-9y+36-12-y=5x-3-9y

1) ...... = 6-2х-6+х = -2х+х= -х2) ......= -3+х-12+у =-15+х+у3) .....= -7+х+4х-20= 5х-274) ..... = -9у+36-12-у=-10у+24