The maximum marks for JEE advanced are not fixed and it is variable it keeps on changing every year therefore to tell you the exact marks is not a good choice it  is sometimes 150 marks will give you a same seat and sometimes 200 marks won't Therefore the true criteria to compare is the rank for IIT Bombay even in the worst case you need to have at least two thousand rank in general category to get into IIT Bombay for courses which more demanded like computer science and engineering or electronics and communication or for that matter electrical engineering you need to be among the top of the advance like 200 rank.