metode subtitusi dari x-y=4 dan 2x+4y=20

x-y = 4 •--> x = 4+y

2x+4y = 20
2(4+y)+4y=20
8+2y+4y=20
8+6y=20
6y = 20-8
6y = 12
y = 12/6
y = 2

x-y = 4
y = x-4

2x+4y=20
2x+4(x-4)=20
2x+4x-16=20
6x=20+16
6x=36
x = 36/6
x = 6