Step-by-step explanation:
[tex]1) \: \: - x + 2y + 2z = - 4 \\ 2z = - 4 + x - 2y \\ z = \frac{ - 4 + x - 2y}{2} \\ \\ 2) \: \: 4x + y - 3z = 13 \\ - 3z = 13 - 4x - y \\ z = \frac{13 - 4x - y}{ - 3} \\ \\ 3) \: \: x - 5y + z = - 23 \\ z = - 23 - x + 5y \\ [/tex]
