#### Answer

$\left\{\begin{array}{llll}
2x & & +z & =9\\
& -y & -z & =5\\
3x & +y & & =8
\end{array}\right.$

#### Work Step by Step

The augmented matrix of the system consists of
the elements of the coefficients matrix to the left,
and the elements of the constants matrix to the right
of (an optional) vertical line:
The system associated with the augmented matrix is
$\left\{\begin{array}{llll}
2x & & +z & =9\\
& -y & -z & =5\\
3x & +y & & =8
\end{array}\right.$