Write the system of linear equations represented by the augmented matrix. Use $x, y,$ and $z,$ or, if necessary, $w, x, y,$ and $z,$ for the variables.
$$\left[\begin{array}{rrrr|r}
4 & 1 & 5 & 1 & 6 \\
1 & -1 & 0 & -1 & 8 \\
3 & 0 & 0 & 7 & 4 \\
0 & 0 & 11 & 5 & 3
\end{array}\right]$$