Tolong bantuannya ya, soalnya ada di photo, dg cara metode substitusi..

8z = -8
z = -1
3y - 2z = -4
3y +2 = -4
3y = -6
y = -2
2x + y +z = -9
2x -2 - 1 = -9
2x = -6
x = -3
x - (y+z) = -3 - (-2+-1) = -3 + 3 = 0 (C)

kalau tidak salah jawabannya adalah bagian c. 0
caranya seperti ini.
8z = -8
z = -1

3y - 2z = -4
3y = -4 +2z
3y = -4 +2(-1)
3y = -4-2
3y = -6
y = -2

2x+y+z =-9
2x -2-1= -9
2x -3 = -9
2x = -6
x = -3

jadi, x-(y+z) = -3 - (-2 +(-1)) = -3 + 3 = 0