How to get 80+ marks within 15 days ?

Which chapters should I study? Should I just focus only on chemistry and try to attend 20 questions with just chemistry or should I study physics and chemistry. I just need 80 marks. I know most of Physical chemistry, organic chemistry i studied but haven't practiced. And in physics I just 30% of all chapters, like I haven't finished any chapters completely. So for 80 marks , in these last 15 days what chapters should I study. I just need to make sure I get these 80 marks no matter what Please help