Himpunan dari persamaan 2x-y=-10 dan 5x+y=-11 dgn metode subtitusi

2x - y = -10
5x + y = -11 => y = -5x - 11

Subtitusi :
2x - y = -10
2x - (-5x - 11) = -10
2x + 5x + 11 = -10
7x = -10 - 11
7x = -21
x = -21/7
x = -3

2x - y = -10
2(-3) - y = -10
-6 - y = -10
-6 + 10 = y
4 = y