Hi Bakshi121092,
You've defined RC as an area that you need to work on (and 'skimming' is a terrible approach for RC) - but it's not clear if that's the ONLY area that you need to work on. Before I can offer you the specific advice that you’re looking for, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied?
2) What study materials have you used so far?
3) You appear to have taken the GMAT at least once already. When did you score 640? Do you purchase an Enhanced Score Report for that Exam?
Goals:
4) What is your goal score?
5) When are you planning to apply to Business School?
6) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich