How Does Charge Redistribution Work in a Conductor with a Cavity?

[JimiJams]

Homework Statement

An initially neutral conductor contains a hollow cavity in which there is a +100nC point charge. A charged rod transfers -50nC to the conductor. Afterward, what is the charge (a) on the inner wall of the cavity wall, and (b) on the exterior surface of the conductor?

Homework Equations

This is more of a conceptual problem for me than mathematical. The answers just don't make sense to me. I'd appreciate if someone could explain the answer and then I can ask followup questions if it still isn't making sense. Thanks a lot!

The Attempt at a Solution

I really don't know how to approach this...

 

[JimiJams]

Let me state, too, that I'm not just being lazy here and just looking for the answer. We don't turn in any homework in our class, it's completely optional. I'm just trying to understand this problem and the best way for me to do it is for someone to explain it (since I have no clue about this one) and then I'll ask questions to make sure it's clear to me.

 

[tiny-tim]

Hi JimiJams!

Tell us what you think the answers are, and what's worrying you about that, and then we'll comment.