Jika Y-x=0 dan 3x-Y=6,maka x+Y=...

y-x = 0 → x-y = 0


eliminasi keduanya :
x-y = 0
3x-y = 6
________ -
-2x = -6
x = 6/2
x = 3
disubstitusikan ke :
x-y = 0
3-y = 0
-y = -3
y = 3


jadi,
x+y = 3+3 = 6