1) define point Q on the line = <2,8,3>
2) define line PQ=<2,8,3>+t<2+7,8+6,3-1> = <2,8,3>+t<9,14,2>
3) define L1 (giiven) = <2,8,3>+t<7,3,-2>
4) 2 intersecting lines define a plane thus PQXL1 = N (plane normal)
5) In 4, use only the direction vector components of PQ and L1
6) Find N to be <-34,-32,-21>
7) Find the plane equation to be -34x-32y-21z=D
8) Find D by setting using point (2,8,3) = -387
9) Equation of plane is 34x+32y+21z=387