\(\left|x-3\right|=\left|5\right|+\left|-7\right|\)
\(\Rightarrow\left|x-3\right|=5+7\)
\(\Rightarrow\left|x-3\right|=12\)
\(\Rightarrow\left[{}\begin{matrix}x-3=-12\\x-3=12\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-12+3\\x=12+3\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-9\\x=15\end{matrix}\right.\)
=>|x-3|=12
=>x-3=12 hoặc x-3=-12
=>x=-9 hoặc x=15