Answer
$x=8,y=-4$
Work Step by Step
Cramer's Rule for $2$ equations in $2$ unknowns says that the system of linear equations is equivalent to the matrix equation $DX=B$ and if $|D|\ne 0$, then the solutions are $x_i=\frac{|D_{x_i}|}{|D|}$ where $D_{x_i}$ can be obtained by replacing the $i$th column of $D$ by $B$.
Hence, we have:
$|D|=12(9)-(-11)(7)=185$
$|D_x|=140(9)-(-11)20=1480$
$|D_y|=12(20)-(140)(7)=-740$
Thus
$x=\frac{|D_x|}{|D|}=8,y=\frac{|D_y|}{|D|}=-4$
