What is the solution?Thank you!

3. Let 2x y + z = 5 and x + y z = 1 be the equations of two planes. a) Find the line of intersection of these two planes using Gauss or Gauss-Jordan. What is the directional vector of the line? b) Find the cross product of the normal vectors of the two planes. Compare your result with your answer in a). What do you notice? 4. Let 11,12 and l3 be lines in R3. We know the following: 0 l2 goes through the origin (0, 0,0) and through the point (1, 2, 1); 0 I1 is parallel to [2; 0 l1 and I3 intersect each other at a single point: (1, 3, 1); 0 l3 has directional vector d3 = [1,1, 2]. a) Find the vector equation and parametric equations for each of the lines. Use a different parameter (T, s, t) for each line. b) Find the angle of intersection between l1 and 13. c) Find the point of intersection of 12 and 13 or show that they are skew