Theo đề bài ta có:
\(\left\{{}\begin{matrix}p+e-1+n=155\\p+e-1-n=31\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2p+n-1=155\\2p-n-1=31\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}p=e=47\\n=62\end{matrix}\right.\\ \rightarrow M:Ag\)
