Trong 2 nguyên tử X,Y ta có :
\(\left\{{}\begin{matrix}2Z+N=58\\Z+N=39\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}Z=19\\N=20\end{matrix}\right.\)
Mặc khác, theo đề ta có :
\(\left\{{}\begin{matrix}Z_X+Z_Y=19\\2Z_X-2Z_Y=6\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}Z_X=11=P_X\\Z_Y=8=P_Y\end{matrix}\right.\)