Percentile = no. of student have marks lesser than you in your board / total no. of students appeared in the exam X 100

Your percentile should be >= 80 or you should have have your board percentage greater than or equal to 75%

And you can check last year cut off of your respective board through below link -

http://josaa.nic.in/webinfo/Handler/FileHandler.ashx?i=File&ii=89&iii=Y

Good Luck!!!