Metode gabungan x + 2y = 2 x - y = -1

x + 2y = 2
x - y = - 1
--------------(-)
3y = 3
y = 1

x - y = - 1
x - 1 = - 1
x = - 1 + 1
x = 0

hp = {0,1}

x +2y -(x -y) :3
3y :3
y :1
maka x:0