Hi Joy,

As per official website,

Merit list for admission to various undergraduate courses will be made based on the results of 10+2 or equivalent examination. a) Merit list will be prepared on the basis of aggregate marks of best four subjects (in terms of marks obtained) along with the marks obtained in the subject in which the candidate is willing to take honours. Calculation will be made on total marks obtained out of 500 (four best subjects : 4x100 plus marks obtained in the subject in which the candidate is willing to take honours i.e. 100) .

Example:
Sample 1: Marks obtained: English-90, Bengali-80, Physics-95, Chemistry-92, Mathematics-98, Biology-90
Best four will be: Mathematics-98, Physics-95, Chemistry-92, Biology/English-90 = 375 out of 400
A candidate willing to take honours in Physics: Marks out of 500 will be: 375 + Physics-95 = 470

For more details:

http://www.visvabharati.ac.in/file/Prospectus2016_Handy%20FINAL.pdf