This is a question from a school textbook (Extended Math for IGCSE by David Reyner), so I'm guessing it shouldn't be too hard to solve for you guys. Anyway, here it is:
In a triangle ABC, a line is drawn parallel to BC to meet AB at D and AC at E. DC and BE meet at X. Prove that: (a) the triangles ADE and ABC are similar. (Done) (b) the triangle DXE and BXC are similar. (Done) (c) AD / AB = EX / XB