I need to find the equation of a plane which passes through P( 1, 2, 0) and which is perpendicular to the planes

2x - 3y + 4z + 1 = 0

and

-x + 2y +4z + 7 = 0

so far I've found the r.n=p form of the above known planes, and calculated that they do in fact intersect, angle of intersection is something like 1.24 rads

what next? please help

thank you