Solve the all parts of given question:
Question: A 15-cm-focal-length converging lens is 20cm to the right of a 5.0-cm-focal-length converging lens. A 2.9-cm-tall object is distance L to the left of the first lens.
Part A: For what value of L is the final image of this two-lens system halfway between the two lenses?
Part B: What is the height of the final image?
Show how you get the answer, so that I can better understand how to do it.