Ta có : $\left\{ \begin{array}{l}13x-15y=-48\\2x+y=29\end{array} \right.$
$⇔\left\{ \begin{array}{l}13x-15y=-48\\30x+15y=435\end{array} \right.$
$⇔\left\{ \begin{array}{l}43x =387\\30x+15y=435\end{array} \right.$
$⇔\left\{ \begin{array}{l}x=9\\y=11\end{array} \right.$