Admission to B.Tech 2018 at Sastra University will be done on the basis of two streams in which stream 1 will be based on JEE Main 2018 score and qualifying exam scores for 70% seats and stream 2 will be based on qualifying exam for 30% seats. Also, to check the complete admission process and how they calculate board percentage for filling up the seats under stream 2, you can go through the below link -

SASTRA Admission

Good Luck!!!!