HPT <=> \(\left\{{}\begin{matrix}xy-3x+10y-30=xy\\xy+5x-10y-50=xy\end{matrix}\right.\)
<=> \(\left\{{}\begin{matrix}-3x+10y-30=0\left(1\right)\\5x-10y-50=0\left(2\right)\end{matrix}\right.\)
Từ (1); (2) => \(2x-80=0\)
=> \(x=40\)
=> \(-120+10y-30=0\)
=> \(y=15\)
Vậy \(x=40;y=15\)