I got a B+ final grade from a [B+, 30%] and [A, 50%] with a remaining 20% participation. What did I get in participation for my final grade to be a B+?

I received a B+ in a course.

I received an A-/B+/B+ which make up 30% of my grade.
I received an A which makes up 50% of my grade.
20% of my grade is participation.

What did I get in participation that makes a B+ final possible from this breakdown?

(Hint: My degree is in the humanities.)