Ta có : $\left\{ \begin{array}{l}3x-y=52\\x+3y=18\end{array} \right.$
$⇔\left\{ \begin{array}{l}3x-y=52\\3x+9y=54\end{array} \right.$
$⇔\left\{ \begin{array}{l}10y=2\\x+3y=18\end{array} \right.$
$⇔\left\{ \begin{array}{l}y=\dfrac{1}{5}\\x=\dfrac{87}{5}\end{array} \right.$