Answer
$X=\left[\begin{array}{rr}
-1 & -1/2\\
1 & 2
\end{array}\right]$
Work Step by Step
$ 2X+A=B\qquad$ ... subtract A from both sides
$2X=B-A\qquad $... multiply both sides with $\displaystyle \frac{1}{2}$
$X=\displaystyle \frac{1}{2}(B-A)$
$B-A=\left[\begin{array}{ll}
2-4 & 5-6\\
3-1 & 7-3
\end{array}\right]=\left[\begin{array}{ll}
-2 & -1\\
2 & 4
\end{array}\right]$
$\displaystyle \frac{1}{2}(B-A)=\left[\begin{array}{ll}
-2/2 & -1/2\\
2/2 & 4/2
\end{array}\right]=\displaystyle \left[\begin{array}{ll}
-1 & -1/2\\
1 & 2
\end{array}\right]$
