mohon di jawab please pake cara

x + y = 1
x = - y + 1
subtitusi ke pers
z + x = 6
z - y + 1 = 6
z - y = 6 - 1
z - y = 5
- y + z = 5

y + z = 3
- y + z = 5
---------------(+)
2z = 8
z = 4

y + z = 3
y + 4 = 3
y = 3 - 4
y = - 1

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

nilai x • y • z = 2 • (-1) • 4 = (-8) ( A )