Diketahui SPDLV : 3x + y = 7 dan 4x +2y = 12, hitunglah nilai 5x -y

3x + y = 7    (x2)
4x + 2y = 12 (x1)
--------------------------
6x + 2y = 14
4x + 2y = 12
--------------------------- -
2x = 2
x = 1

3 + y = 7
y = 4

5x - y = 5(1) - 4 = 5 - 4 = 1

nilai 5x - y = 1