4x - 3y=-3 DAN 2X - 5Y=9,maka nilai x-y adalah...

4x - 3y = -3 (x 1)
2x - 5y = 9 (x 2)
------------------------------>> hilangkan satu variabel
4x - 3y = -3
4x - 10y = 18 -
------------------------------>> dikurangi

7y = -21
y = -3

4x - 3(-3) = -3
4x + 9 = -3
4x = -3 - 9
4x = -12
x = -3