posted by Lily .
Did you notice that your third equation has the same normal as the third one?
So visually I see two parallel planes intersected by third non-parallel plane, namely the second equation.
So solve equations 1 and 2, and express them in parametric form
repeat by solving equation 2 and 3
these two lines will be parallel
hint: I got direction numbers of (19,5,-11) for the lines.