exercice matrice merci de laide (trouver la matrice x)

[tex]\left(\begin{matrix}1&2\\1&1\end{matrix}\right)-3X=X+\left(\begin{matrix}-8&3\\5&-3\end{matrix}\right)\\\\ 3X+X=\left(\begin{matrix}1&2\\1&1\end{matrix}\right)-\left(\begin{matrix}-8&3\\5&-3\end{matrix}\right)\\\\ 4X=\left(\begin{matrix}1-(-8)&2-3\\1-5&1-(-3)\end{matrix}\right)\\\\ 4X=\left(\begin{matrix}9&-1\\-4&4\end{matrix}\right)\\\\ X=\left(\begin{matrix}9/4&-1/4\\-4/4&4/4\end{matrix}\right)\\\\ \boxed{X=\left(\begin{matrix}9/4&-1/4\\-1&1\end{matrix}\right)}[/tex]