2(x+y)-7(x+y)+3=0 2x-3y=-1
2(x+y)-7(x+y)+3=0 2x-3y=-1 -5(x+y)+3=0 2x-3y=-1 -(5x+5y)+3=0 2x-3y=-1 -5x-5y+3=0 2x-3y=-1 -5x-5y=-3 2x-3y=-1 (-5x-5y)(-3)=(-3)(-3) (2x-3y)5=-1 -(-5x-5y)*3=3*3 2x-3y=-1