The focus is (0,-6/4), from the definition of a parabola. Now find the equation of the line joining the focus and (6,-6), you should get y + 1.5 = -3/4 x.
Now solve this simultaneously with the parabola to find points of intersection, and you'll get two of them- one will be (6,-6) and the other one will be X. Try and do it yourself without looking at any answers.