About New Contents that needed to be add

Hello, I have questions from my teachers that I manage to answer even though I never learned it. But I'm not sure If Im correct. Also I have terrible writing and I'm gonna post here what my teacher homework and my answers to it.

This was my homework given by my teacher, I never have learned that concentric circle in khan academy, I tried to search and still nothing..

sorry I couldn't upload my answers since it was 2mb+ in sized. 

would you give me answers and solution plus explanation and If this wasn't really on khan academy's content. I hope they add it