Verified answer

Put 3 in Set D;

Put 3, 18, 23 in Set Z;

If we combibe/union Sets D & Z, there are common numbers such as 3, 18, 23

DUZ = {3, 18, 23} because the U represents union, which is all the numbers that are included in both sets. The answer is not {3, 3, 18, 23} because you cannot repeat numbers in a set.

D union Z would be all the elements in D and Z. Don't list the same element twice as it is not needed. Ergo, DUZ {3,18,23}.