contoh substisusi x+2y=9 2x-y=8 tlong dibantu y

x + 2y = 9
Maka x = 9 - 2y
Dimasukkan ke persamaan kedua.
2x - y = 8
2 (9 - 2y) - y = 8
18 - 4y - y = 8
18 - 5y = 8
10 = 5y
y = 2

x +2y =9 l x2l 2x + 4y =18
2x - y = 8l x1l 2x -    y = 8  
5y = 10
y = 10/5
y = 2
x +2y = 9
x +2(2) = 9
x + 4 = 9
x = 9 - 4 
x = 5