Mohon dijawab dengan 3 Langkah

x+y-z=0
x-y-z=4
x+2y+z=-4

x+y-z=0
x-y-z=4
----------- -
2y=-4
y=-2

x-y-z=4
x+2y+z=-4
--------------- -
-3y-2z=8
substistusi
-3y-2z=8. --> y=-2
-3(-2)-2z=8
-6-2z=8
-2z=14
z=-7

x+y+z=0
x-2-7=0
x=9