2x+3y=12 dan y=3-x dengan cara subtitusi

2x + 3y =12 .........(1)
y =3 - x
x +y = 3 ................(2)

# (1&2) 2x + 3y = 12 | 1
x + y = 3 - | 2
# 2x +3y =12
2x +2y = 6 -
y = 6

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