Answer
See below
Work Step by Step
We find the determinant
$27-28 =-1 $
Use the formula
\[
M=\frac{1}{ad-bc}
\left[ {\begin{array}{cc}
d &-b \\
-c & a \\
\end{array} } \right]
\]
to get
\[
M=
\left[ {\begin{array}{cc}
-9 & 4 \\
7 & -3 \\
\end{array} } \right]
\]