Given the following set:

A = {2,3,4,5}
B = {5,6,7,8}
Find the Complement of set A union B.

The complement of set A union B, denoted by (A ∪ B)', can be found by taking all elements that are not in the set A union B.

So, first we need to find A ∪ B, which is the set of elements that are in either set A or set B, or in both:

A ∪ B = {2,3,4,5,6,7,8}

Next, we find the complement of A ∪ B by taking all elements that are not in A ∪ B:

(A ∪ B)' = {1,9,10,11,...}

In this case, we cannot provide a finite list of elements in the complement of A union B because it contains all elements that are not in A union B.