\(\Leftrightarrow\left\{{}\begin{matrix}-3x+9y=-12\\3x+2y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}11y=-11\\x-3y=4\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y=-1\\x-3.\left(-1\right)=4\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=-1\end{matrix}\right.\)