Question 202682
First, let's find the set A'. So form the set of elements that are in U but NOT in A:


*[Tex \LARGE A'=\left\{22, 24, 26, 28, 30, 31\right\}] 



Do the same for B'. List the elements in U but NOT in B:


*[Tex \LARGE B'=\left\{21, 23, 24, 26, 27, 30, 31\right\}] 



Now to find *[Tex \LARGE A' \cup B'], just combine the two sets A' and B' (and remove duplicate elements) to get



*[Tex \LARGE A' \cup B'=\left\{21, 22, 23, 24, 26, 27, 28, 30, 31\right\}]