Answer
$x=1.5,y=2$
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:
$|D|=6(7)-(12)(4)=-6$
$|D_x|=33(7)-(12)20=-9$
$|D_y|=6(20)-(33)(4)=-12$
Thus
$x=\frac{|D_x|}{|D|}=1.5,y=\frac{|D_y|}{|D|}=2$
