Consider the following pairs of lines. Determine whether the lines are parallel or intersecting. If the lines intersect, then determine the point of intersection.

a. x = 1 + s, y = 2s and x = 1 + 2t, y = 3t.

b. x = 2 + 5s, y = 1 + s and x = 4 + 10t, y = 3 + 2t.

c. x = 1 + 3s, y = 4 + 2s and x = 4 - 3t, y = 6 + 4t.