\(\left|5+x\right|+x=-5\)
\(\Rightarrow\left|5+x\right|=-5-x\)
\(\Rightarrow\left[{}\begin{matrix}5+x=5+x\\-5-x=5+x\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)
\(\Rightarrow\left|5+x\right|=-5-x\)
\(\Rightarrow\left[{}\begin{matrix}5+x=5+x\\-5-x=5+x\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)