\(\left(3-x\right)^{2018}=\left(x-3\right)^{2017}\)
\(\Rightarrow\left(x-3\right)^{2018}-\left(x-3\right)^{2017}=0\)
\(\Rightarrow\left(x-3\right)^{2017}\left(x-3-1\right)=0\)
\(\Rightarrow\left(x-3\right)^{2017}\left(x-4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-3=0\Rightarrow x=3\\x-4=0\Rightarrow x=4\end{matrix}\right.\)