math set notations

Question

Suppose Set A contains 44 elements and the total number elements in either Set A or Set B is 68. If the Sets A and B have 5 elements in common, how many elements are contained in set B?

Answer 1

#A = number of objects in A

#(A or B) • #A + #B - #(A and B) (the second term is to account for double counting)

68 = 44 + #B - 5

#B = 29