\left\{_\begin{array}{l}2(x_ _y)_=_120_\\_xy_=_675_\\_\end{array}_\right__\Leftrightarrow_\left\{_\begin{array}{l}y_=_60_-_x_\\_x(60_-_x)_=_675_(*)_\\_\end{array}_\right_=