Physics 2 (E&M) homework problem

I took the test earlier today and thankfully there weren't any problems like that but it was still hard as SH*T. This is the first time in my life I'm going to have to study many days in advance before a test as I can't just rely on my "academic talent" any more. I just can't wait to get this electricity junk over with and move onto Physics 3. I wish my classes involved working on cars but you have to join an Automotive Engineers club for that...LOL