Câu 2:
\(\left\{{}\begin{matrix}P+N+E=52\\P=E\\P+E=34\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P=34\\2P+N=52\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=17\\N=18\end{matrix}\right.\Rightarrow A=Z+N=17+18=35\left(đ.v.C\right)\)
Câu 3:
\(\left\{{}\begin{matrix}P+N+E=114\\P=E\\\left(P+E\right)-N=26\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2P+N=114\\2P-N=26\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=35\\N=44\end{matrix}\right.\\ \Rightarrow A=Z+N+35+44=79\left(đ.v.C\right)\)
Câu 4:
\(\left\{{}\begin{matrix}P+N=65\\N-P=5\\P=E\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}P=E=Z=30\\N=35\end{matrix}\right.\\ \Rightarrow A=Z+N=30+35=65\left(đ.v.C\right)\)
