NSIT and DTU are one of the premier institutes in the country and so naturally have a high cut off. As of now, the comparative performances of students are not known and so rank via percentiles can't be determined. 75 percentile will be enough to clear JEE Mains (for General category), but to get a seat in DTU or NSIT you have to aim for 90 percentile or more. Especially if you are aiming for courses like CSE or Mechanical Engineering. 

Good luck.

Hi Sonakshi

From this year Guru Gobind singh Indraprastha University started taking admission through Jee Mains and it is a good government college in delhi and there are some many good government engineering college which are affliated through GGSIPU Delhi.So you try to fill the application form Asap on :-  Ipu.ac.in

Hope it Helps