subtitusi dari 2x + 3y = -15 dan x - 4y = 31

Maka didapatkan x = 3 dan y = -7

1. 2x + 3y = 15
subtitusi "y"
2x + 3y = 15
3y = 15 - 2x
3 = 15 - 2x
2x = 15 - 3
2x = 12
x= 12/2
x= 6
subtitusi "x"
2x + 3y = 15
2.6 + 3y = 15
4 + 3y = 15
3y = 15 - 12
y = 3/3
y = 1