Answer
$x=\left[\begin{array}{ll}
5 & 17\\
-5 & 45/2\\
-11 & -2
\end{array}\right]$
Work Step by Step
$ 2X+5A=B\qquad$ ... subtract $5A$ from both sides
$ 2X=B-5A\qquad$ ... multiply both sides with $\displaystyle \frac{1}{2}$
$ X=\displaystyle \frac{1}{2}(B-5A)$
$X=\displaystyle \frac{1}{2}\cdot(\left[\begin{array}{ll}
-5 & -1\\
0 & 0\\
3 & -4
\end{array}\right]-5\displaystyle \cdot\left[\begin{array}{ll}
-3 & -7\\
2 & -9\\
5 & 0
\end{array}\right]) $
$X=\displaystyle \frac{1}{2}\cdot\left[\begin{array}{ll}
-5-5(-3) & -1-5(-7)\\
0-5(2) & 0-2(-9)\\
3-5(5) & -4-5(0)
\end{array}\right]$
$X=\displaystyle \frac{1}{2}\cdot\left[\begin{array}{ll}
10 & 34\\
-10 & 45\\
-22 & -4
\end{array}\right]$
$x=\left[\begin{array}{ll}
5 & 17\\
-5 & 45/2\\
-11 & -2
\end{array}\right]$
