It's okay, I have already solved this problem by myself.
I'm sorry I'm asking this but I'm weak in this area.
Given a parallelogram with vertices A=(1,0,-2), B=(-1,1,2), C=(3,4,0) and
D=(1,5,4) write the scalar equation of the plane p passing through point A that also contains the line L. The line L is given by the parametric equations x=1+4t, y=5+3t and z=4-2t.
This question is urgent because I have an exam tomorrow!!
Edit: Further thoughts:
Maybe if it helps, the symmetric equations of the line L passing through D and parallel to the segment BC are:
(x-1)/4=(y-5)/3=(z-4)/-2
Also the apex D is opposite to the point A.