my mains score was 80 and the paper was tough then what is my percentile
Dear aspirant,
I would like to tell you one thing that apart from your preparation level, your marks scored there is one other factor that determines your destiny and that is the luck factor .
As you mentioned that your paper was tough but if in your shift the candidates are more intelligent then it won't affect the rank much. So, technically it doesn't matter that much if you score a bit low in the tough paper.
There are shifts where people get high rank even in low score and easier paper. So, as per my knowledge and prediction you would get percentile around 90.