Diketahui sistem persamaan linier: x+y+z=-6 x-2y+z=3 -2x+y+z=9 Nilai dari 2x-3z adalah.... a.-16 b.-4 c.2 d.4 e.16 Tolong jawab sama caranya

x + y + z = - 6
x - 2y + z = 3
-------------------(-)
3y = - 9
y = - 3

x + y + z = - 6
- 2x + y + z = 9
---------------------(-)
3x = - 15
x = - 5

subtitusi
x + y + z = - 6
- 5 - 3 + z = - 6
- 8 + z = - 6
z = - 6 + 8
z = 2

nilai
2x - 3z
= 2(-5) - 3(2)
= - 10 - 6
= - 16 ( A )