Jika x + 3y = 5 dan x + y = 3, maka x – y = ...

eliminasi

x+3y = 5
x+ y. = 3
------------- -
2y = 2
y = 1

subtitusikan

x + y = 3
x + 1 = 3
x = 3-1
x = 2


maka x - y
2-1 = 2