f:
\(\left\{{}\begin{matrix}\left(x-15\right)\left(y+2\right)=xy\\\left(x+15\right)\left(y-1\right)=xy\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}xy+2x-15y-30=xy\\xy-x+15y-15=xy\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}2x-15y=30\\-x+15y=15\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=45\\15y-x=15\end{matrix}\right.\)
=>\(\left\{{}\begin{matrix}x=45\\15y=45+15=60\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=45\\y=4\end{matrix}\right.\)