Hi Pawan!

The best of four subjects should include one language subject, main subject related to the stream inn which candidate wants admission and other two academic or elective subjects. If in 12th you have mathematics, then you can include it in best of four subjects (if it is related to your stream then it is mandatory to count its marks). For more detailed information, visit here:

https://university.careers360.com/articles/delhi-university-admissions-how-calculate-best-of-four-marks

Thankyou!