DeMorgans Law question

Question

Let U be a universal set with disjoint subsets A and B. Suppose n(U) = 100, n(Ac) = 41, and n(Bc) = 88. Find n((A ∪ B)c).

The "c" stands for compliment. I am having a hard time answering this question, any help?

Answer 1

Because sets are disjoint, n(A)=100-41=59 and n(B)=100-88=12

n(AUB)=59+12=71. N((AUB)c)=100-71=29