As per the official website of the St. Xaviers College, Kolkata, the eligibility for the course of BSc Hons. in Mathematics is provided below:

• COMPULSORY SUBJECT IN 10+2 : Mathematics
• AGGREGATE CALCULATION: Mathematics+ Any 3
• The selection process for the course is On the basis of index calculated with the board marks in +2 level.
• The index calculation for the BSc Mathematics is 2 x MATHEMATICS% + AGG% (OUT OF 300).

For the St. Xaviers College, Kolkata you can follow the link below:

https://www.careers360.com/colleges/st-xaviers-college-kolkata

For the official website visit:

https://www.sxccal.edu/eligibility-criteria/

** On the official website, there are no information regarding the Applied Mathematics, you can contact the college authorities in order to know more specifically from the college authorities.

I hope this helps.