Ta có:
\(\left\{{}\begin{matrix}P+e=22\\p+e\\p+e-n=10\end{matrix}\right.\)
=>p=e=11;n=12
Ta có:
\(\left\{{}\begin{matrix}p+e+n=22\\p+e-n=10\\p=e\end{matrix}\right.\)
=>p=e=8;n=6
theo bài ra ta có
\(\left\{{}\begin{matrix}2p+n=22\\2p-n=10\end{matrix}\right.\)<=> \(\left\{{}\begin{matrix}p=e=8\\n=9\end{matrix}\right.\)
vậy p=e=8, n=9