Answer
$x=118, y=-205$
Work Step by Step
Rewrite our system of equations in matrix form:
$\begin{bmatrix}
7 & 4\\
5 &3
\end{bmatrix}.\begin{bmatrix}
x\\
y
\end{bmatrix}=\begin{bmatrix}
6\\
-25
\end{bmatrix}$
$\begin{bmatrix}
x\\
y
\end{bmatrix}=\frac{1}{21-20}\begin{bmatrix}
3&-4\\
-5 &7
\end{bmatrix}.\begin{bmatrix}
6\\
-25
\end{bmatrix}$
$\begin{bmatrix}
x\\
y
\end{bmatrix}=1\begin{bmatrix}
118\\
-205
\end{bmatrix}$
$\begin{bmatrix}
x\\
y
\end{bmatrix}=\begin{bmatrix}
118\\
-205
\end{bmatrix}$
Hence, $x=118, y=-205$
