I never like these questions ...

(1) Consider the cross product of thenormalsof the plane. The resultant vector should be parallel to the line of intersection (can you think why?).

(2) Recall that a plane can be defined by the equation: where is a vector perpendicular to the plane. The direction vector we found for the line of intersection is perpendicular to the desired plane so why not use it as our vector ? Now, since it passes through the origin, we know that is satisfies the equation of the plane. This should be enough information.