z=x+y-2
x-y+2*(x+y-2)=3 x-y+2*x+2*y-4=3 3*x+y=7 y=7-3*x
x-2*y+x+y-2=1 2*x-y=3 2*x-(7-3*x)=3 2*x-7+3*x=3 5*x=10 x=2
y=7-3*2=1
z=2+1-2=1
z=x+y-2
x-y+2*(x+y-2)=3 x-y+2*x+2*y-4=3 3*x+y=7 y=7-3*x
x-2*y+x+y-2=1 2*x-y=3 2*x-(7-3*x)=3 2*x-7+3*x=3 5*x=10 x=2
y=7-3*2=1
z=2+1-2=1