a) \left\{\begin{matrix} 3x^{2}-y^{2}-5x+3y=4 & \\ 3y^{2}-x^{2}-5y+3x=4 & \end{matrix}\right. b) \left\{\begin{matrix} x+xy+y=11 & \\ xy(x+y)=30 & \end{matrix}\right.