Last question to my quiz! I need help.

Question

9. Solve the system by substitution.

{-x – y – z = -8
{-4 + 4y + 5z = 7
{2x + 2z = 4

Answer 1

Eq3: 2x + 2z = 4.
Z = 2-x.

In Eq1 replace z with 2-x.
-x -y - (2-x) = -8
-x - y -2 + x = -8
Y = 6.

In Eq2, replace y with 6 and solve for z:
-4 + 4*6 + 5z = 7.
Z = -13/5.

Z = 2-x.
-13/5 = 2-x
X = 2 + 13/5 = 23/5.
(x,y,z) = (23/5, 6, -13/5).