Answer
$\left\{\begin{array}{l}
3x=6\\
-3x+y=-7
\end{array}\right.$
Work Step by Step
The product on the LHS is between a 2$\times\underline{2}$ and a $\underline{2}\times$1 matrix,
resulting in a 2$\times$1 matrix:
$\left[\begin{array}{l}
3x+0y\\
-3x+y
\end{array}\right]$
Equating matrices (equating corresponding elements),
we have the system
$\left\{\begin{array}{l}
3x=6\\
-3x+y=-7
\end{array}\right.$