Помогите решить систему уравнения

$\left \{ {{ x^{2}- xy+ y^{2} =63} \atop {x+y=-3}} \right. \\ \left \{ {{ x^{2}- xy+ y^{2} =63} \atop {x=-3-y}} \right. \\ \left \{ {{ (-3-y)^{2}- (-3-y)y+ y^{2} =63} \atop {x=-3-y}} \right. \\ \left \{ {{ 9+6y+y^2+3y+y^2+ y^{2} =63} \atop {x=-3-y}} \right. \\ \left \{ {{ 3y^2+9y+9 =63} \atop {x=-3-y}} \right. \\ \left \{ {{ 3y^2+9y-54=0} \atop {x=-3-x}} \right. \\ \left \{ {{ y^2+3y-18=0} \atop {x=-3-y}} \right. \\ \\ y^2+3y-18=0 \\ y_1+y_2=-3 \\ y_1y_2=-18 \\ y_1=-6 \\ y_2=3 \\ \\$

$\begin{cases}y_1=3\\ y_2=-6\\ x=-3-y\end{cases} \\ \begin{cases}y_1=3\\ y_2=-6\\ x_1=-3-3 \\ x_2=-3-(-6)\end{cases} \\ \begin{cases}y_1=3\\ y_2=-6\\ x_1=-6 \\ x_2=3\end{cases} \\$

Ответ: х=3 у=-6 и х= -6 у=3