x=2y+8 dan 2x=y-11 menggunakan metode substitusi

x = 2y + 8
2x = y - 11
2(2y + 8) = y - 11
4y + 16 = y - 11
4y - y = - 16 - 11
3y = - 27
y = -9
x = 2y + 8
x = 2(-9) + 8
x = - 10