Write the System of Linear Equations Represented by the Augmented $\left[ \begin{array} { l l l : l } 1 & 2 & 1 & - 5 \\0 & 1 & 2 & - 6 \\0 & 0 & 1 & - 1\end{array} \right]$

Write the system of linear equations represented by the augmented matrix. Then use back-substitution to find the solution. Use variables x , y , and z . $\left[ \begin{array} { l l l : l } 1 & 2 & 1 & - 5 \\0 & 1 & 2 & - 6 \\0 & 0 & 1 & - 1\end{array} \right]$

A) $\left\{ \begin{array} { r } x + 2 y + z = - 5 \\y + 2 z = - 6 \\z = - 1\end{array} \right.$
$( - 4,4 , - 1 )$
B) $\left\{ \begin{array} { r } x + 2 y + z = - 5 \\y + 2 z = - 6 \\z = - 1\end{array} \right.$
$( - 4,4 , - 1 )$ .
C) $\left\{ \begin{array} { r } x + 2 y + z = - 5 \\y + 2 z = - 6 \\z = - 1\end{array} \right.$
$( 4,4 , - 1 )$
D) $\left\{ \begin{array} { r } x + 2 y + 2 z = - 5 \\y + z = - 6 \\z = - 1\end{array} \right.$
$( 4,4 , - 1 )$
E) $\left\{ \begin{array} { r } x + 2 y + z = - 5 \\y + 2 z = - 6 \\z = - 1\end{array} \right.$
$( 4 , - 4 , - 1 )$ .