\(\Leftrightarrow\left|13-x\right|=9\Leftrightarrow\left[{}\begin{matrix}13-x=9\\x-13=9\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=22\end{matrix}\right.\)
=>|13-x|=9
\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=22\end{matrix}\right.\)