Greeting Aspirant,

The Percentage For Best of Four is Calculated by Adding Marks in English + Marks in Other Top 3 Subjects divided by 4. The Other Top subjects can be any, even Physical Education or your Major subject.

There is no Advantage or Disadvantage of Using Major subject or Additional subject while calculating Best of 4.

Example: If you have 5 major Subject  and 3 Additional subject and you have scored More in additional as compared to Major subject. Even in this case Your Marks in English + Marks in Top 3 Subjects will be Calculated ( It Does not matter if all the subjects are additional)

Hope My Answer Helped You.

Best Of Luck For Future.