In the diagram above, what will happen if the government sets the price for rent at point b?

I would love to help you but i can not see the diagram you are talking about , if you provide me with one I'll try my best to help

It depends on the subject for me. some exams are easier than others so i usually go through it and answer questions i know based on my general knowledge, then double check after. going through the lesson can a lot  because the exams can be  very lesson-specific, but sometimes they are ridiculously long so a lot of people don't take the time. i did find that, when i went through the lessons, i was making 100's on my exams vs strictly using + the internet and  i make 90's.