Grade scale:
A → 100-90
B → 89-80
C → 79-70
D → 70
F <70
That being said to see your grade, add all your grades up then divide it by how many grades you have.
That being said, if you add all your grades then divide it by how many grades you have, you should have a 85.6 as your average.
Hence, your average is a B.