Câu 1:
\(\left\{{}\begin{matrix}P+N+E=122\\N=P+11\\P=E\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=122\\N-P=11\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=37\\N=48\end{matrix}\right.\\ \Rightarrow A=Z+N=37+48=85\left(đ.v.C\right)\)
Bài 2:
\(\left\{{}\begin{matrix}P+N+E=155\\P=E=Z\\\left(P+E\right)-N=33\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=155\\2P-N=33\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=47\\N=61\end{matrix}\right.\\ \Rightarrow A=Z+N=47+61=108\left(đ.v.C\right)\)
Câu 3:
\(\left\{{}\begin{matrix}P+N+E=52\\P=E\\P+N=35\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=52\\P+N=35\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=17\\N=18\end{matrix}\right.\)
Câu 4:
\(\left\{{}\begin{matrix}P+N+E=58\\N-P=1\\P=E\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=58\\N-P=1\end{matrix}\right.\\\Leftrightarrow\left\{{}\begin{matrix}P=E=Z=19\\N=20\end{matrix}\right.\\ \Rightarrow A=Z+N=19+20=39\left(đ.v.C\right)\\ \Rightarrow KH:^{39}_{19}K\)
