Answer
$\left\{\begin{array}{l}
2x-z=6\\
3y=9\\
x+y=5
\end{array}\right.$
Work Step by Step
The product on the LHS is between a $3\times\underline{3}$ and a $\underline{3}\times$1 matrix,
resulting in a $3\times 1$ matrix:
$\left[\begin{array}{l}
2x+0y-1z\\
0x+3y+0z\\
1x+1y+0z
\end{array}\right]$
Equating matrices, (equating corresponding elements),
we have the system
$\left\{\begin{array}{l}
2x-z=6\\
3y=9\\
x+y=5
\end{array}\right.$
