The problem is;

Tim is pointing a lazer beam from the point A in the direction u towards a mirror whose shape is given by G(x,y,z)=0. After reflecting from the mirror, where will the beam show up on the plane X=10

A=(2,8,3) u=<1,-3,0> and G(x,y,z) = X^2 + Y^2 - Z^2 -11

I have a few ideas on how to do it but i keep running into walls with them, any help would be appreciated