Central Board Of Secondary Education [CBSE] — Regarding low marks in class 10

Address: Delhi

Respected sir/mam
I am ujjwalkumar mahto students of
Gourav Awas Uchcha vid Bansidih, chas, bokaro, jharkhand
Sir I never got below 90%percent in any exam of our school and I also got 93%percent in our periboard exam that conducted by the school but in the 10th board final exam I got only 61% how is this possible
So I request to you sir please improvement my marks