Do how many problems you need to do in order to finish QR on the Destroyer in 7 days. I think you may have to do at least 40 problems a day? Do as many as possible. Do you have Math Destroyer? If you do, then you are short on time, so you have to keep yourself in a tight schedule. So first, do everything on the Destroyer QR section and learn everything you need to learn. If you are having trouble, you may have to do all of that again one more time. Then, do math destroyer (if you have it) or bootcamp 2 tests a day for the next 7 days.
For ochem, same thing. First, see how many tests / problem sets you have available. What I would do is I multiply that by two, because I want to do them twice to make sure I learn it 100%. It helps! Then divide that by how many days I have left, to calculate how many I have to do per day.
If you feel like that's too much, that's okay, don't panic. Don't be stressed. Just do as much as you can and don't lose concentration! Start from the basics and learn one thing after another. You can do it!