Two part dream

The first part of this dream started out with me being in a classroom. I've had numerous dreams like this before and even logged some in here at USM. A classmate was helping me study for some type of exam that we were having. I recognized my classmate as a girl that I actually did study with in college. I remember her showing me some of the equations an reciting them very quickly as we had little time before the exam started. She had her notes out and there were about 6 "formulas" that she was going over with me that had just "A" and "B" in them. Like A/B = A*A!/B*B! and five others. She was saying "A over B equals AB over AB" and many other things like that that didn't make much sense. However, I got the feeling that this was not Math but more like Chemistry or some type of science because once the test was passed out, there were word problems asking things that were like in Physics. After the test was passed out, I had a terrible sinking feeling, there was no way to pass this but I put what I remembered which was close to nothing and guessed on the word problems. This part of the dream ended with the teacher grading the exams but keeping only mine as an example of what happens when you don't study...

The second part, I was in a high rise building at first and I was with an ex-girlfriend and I was really delighted to see her as we stayed friendly even through our breakup. As we walked together through this building, I noticed that the carpet was red and there were dim canister lights lining the middle of the hall which seemed to go on forever. Finally, we arrived at the elevator and all the while we were talking and laughing probably catching up on lost time. The elevator was one of those that has a window so that you can see outside as you are traveling in it. I noticed that the city we were in was very big but dirty looking. I take it that it was sunset at the time but the sky was a brownish color with thick clouds that were surrounding the sun just enough to let some light through. The buildings were dirty like they were never cleaned and the concrete was tarnished. We were walking through a city street when suddenly my ex says that our car is in one lot and I say that it was in another. We separated and both went to find where we thought the car was. I found the car and started it to go looking for my ex-gf and then suddenly, there were other people in the car with me, a man and a woman, who apparently were friends of mine. Suddenly, I got a bad feeling as I was looking for my ex and I realized that this car I was driving was not mine. It looked like it however it was not. The guy asked me, "How do you know this is not your car?" I replied, "There's no tint on the window and the seat is not torn in the back like mine." We abandoned the car and left on foot to look for my ex but she was nowhere to be found. The dream ended with a view of me and the 2 people from above and the view just kept ascending until the clouds covered us...

It was nice to see the ex-gf, she was always really nice.