Answer
See below
Work Step by Step
Apply Cramer's Rule for a $2 \times 2$ system $Ax=b$ where $A=\begin{bmatrix}
a_1 & b_1\\a_2 & b_2
\end{bmatrix}$ and $b=\begin{bmatrix}
c_1 \\c_2
\end{bmatrix}$
Obtain $x_1=\frac{\begin{vmatrix}
c_1 &b_1\\c_2 &b_2
\end{vmatrix}}{\begin{vmatrix}
a_1 & b_1\\a_2 & b_2
\end{vmatrix}}=\frac{\begin{vmatrix}
3 &1\\1&2
\end{vmatrix}}{\begin{vmatrix}
-3 & 1\\1&2
\end{vmatrix}}=-\frac{5}{7}$
$x_1=\frac{\begin{vmatrix}
a_1 & c_1\\a_2 &c_2
\end{vmatrix}}{\begin{vmatrix}
a_1 & b_1\\a_2 & b_2
\end{vmatrix}}=\frac{\begin{vmatrix}
-3 &3\\1&1
\end{vmatrix}}{\begin{vmatrix}
-3 & 1\\1&2
\end{vmatrix}}=\frac{6}{7}$
