#### Answer

\begin{cases}7x+4z=-13 \\ y-5z=11 \\ 2x+7y=6 \end{cases}

#### Work Step by Step

The entries in the first row of the left side of the vertical in the augmented matrix correspond to the coefficients of the variables in the first equation. The entry in the first row on the right side of the vertical corresponds to the right side of the first equation. Therefore the first equation is $7x+4z=-13$. Similarly the second and third equations become, $ y-5z=11$ and $ 2x+7y=6$ respectively.