Diketahui 5x+2y=-3 dan 7x+8y=1 jadi nilai x-y adalah

5x + 2y = -3 | × 7 |
7x + 8y = 1 | × 5 |

35x + 14y = -21
35x + 40y = 5
———————– –
-26y = -26
y = 1

5x + 2y = -3
5x + 2(1) = -3
5x + 2 = -3
5x = -3 -2
5x = -5
x = -1

x – y
= -1 -1
= -2 (A)