The best of 4 in DU for BA programme is calculated by taking English and 3 other subjects in which the candidate has scored the best.

Your best of 4 will be calculated by taking English, Political Science, Geography and the 4th is optional between fine arts and economics. As some colleges in DU tend to deduct 2.5% from the cut off. (As it is an additional subject and has a 60:40 component in Theory: Practical)

83+84+86+95/4= 87% (and the 2.5% decrease will result in 84.5% )

Hope this was helpful and good luck!