Question: Find the number of elements in A1 ∪ A2 ∪ A3 if there are 100 elements in A1, 1000 in A2, and 10,000 in A3 if
a) A1 ⊆ A2 and A2 ⊆ A3.
b) the sets are pairwise disjoint.
c) there are two elements common to each pair of sets and one element in all three sets.