Answer
$X=\left[ \begin{matrix}
-1 & 3 \\
-1 & \frac{9}{2} \\
-1 & -2 \\
\end{matrix} \right]$
Work Step by Step
Consider the matrix equation, $2X+A=B$.
This implies that, $2X=B-A$ or $X=\frac{B-A}{2}$.
Now consider the following,
$\begin{align}
& X=\frac{B-A}{2} \\
& =\frac{1}{2}\left( \left[ \begin{matrix}
-5 & -1 \\
0 & 0 \\
3 & -4 \\
\end{matrix} \right]-\left[ \begin{matrix}
-3 & -7 \\
2 & -9 \\
5 & 0 \\
\end{matrix} \right] \right) \\
& =\frac{1}{2}\left( \left[ \begin{matrix}
-2 & 6 \\
-2 & 9 \\
-2 & -4 \\
\end{matrix} \right] \right) \\
& =\left[ \begin{matrix}
-1 & 3 \\
-1 & \frac{9}{2} \\
-1 & -2 \\
\end{matrix} \right]
\end{align}$
