Ta có \(\left\{{}\begin{matrix}2p+n=40\\2p.\dfrac{7}{13}=n\end{matrix}\right.=>\left\{{}\begin{matrix}2p+n=40\\2p=\dfrac{13}{7}n\end{matrix}\right.=>\dfrac{13}{7}n+n=40\)
=> \(n\left(\dfrac{13}{7}+1\right)=40=>n.\dfrac{20}{7}=40=>n=14\)
=> 2p = 26
=> p = 13
Vậy Y là Nhôm ( Al)