Question

"Give examples of when you would multiply combinations and when you would add combinations"

Answer 1

are are talking about sequence and series for calculus ?

Answer 2

Yes, like permutations and computations(nCr and nPr)

Answer 3

well- P A and P B would be multiplying given that A and B are disjoint, and P A or P B would be adding, given that A and B are disjoint.