Central Board Of Secondary Education [CBSE] — Valuation of CBSE class 12th result.

Address:

Jaipur

CBSE generated results on 3 year's marks this year because of covid and created lots of mistakes in that. Mistakes in grading and avg marks for students. Due to school impression they created worst results of bright students.
In practical I got almost full marks in every subject but in theory part they degraded me.
In economics I got 38/70.
How it happened I want to know.
I scored 8.8 CGPA in 10th and 86% in 11th. So, how it could happen that i score only 38 marks???