a) \(\left\{{}\begin{matrix}2Z+N=52\\2Z-N=16\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}Z=17\\N=18\end{matrix}\right.\)
b) \(\left\{{}\begin{matrix}2Z+N=95\\2Z-N=25\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}Z=30\\N=35\end{matrix}\right.\)