jika nilai x dan y memenuhi sistem persamaan 2x + y = 5 dan x + 4y = -1 maka nilai x - y =

2x + y = 5......(1)
x + 4y = -1......(2)

Eliminasi ke pers (1) dan (2)
2x + y = 5 [×1 ] 2x + y = 5
x + 4y = -1 [×2] 2x + 8y = -2
______________________-
-7y = 7
y = 7/-7
y = -1

Substitusi ke pers (2)
x + 4y = -1
x + 4(-1) = -1
x + (-4) = -1
x = -1+4
x = 3

Nilai x - y = 3 - (-1) = 3 + 1 = 4


Semoga membantu.