can I do graduation with math after doing graduation with biotechnology
Yes definitely! Mathematics and the engineering fields like Biotechnology in general are very much interlinked and you can pursue one after or before completing a graduation in the other subject. So, essentially yes, you can do a graduation in maths after completing your graduation in biotechnology.
You can also use our college predictor to see your chances in all the colleges:
https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer
Hope I have answered your question. All the best!