Question

Given A = {a, e, i, o, u} and B = {a, l, g, e, b, r}, find A ∪ B.

Answer 1

A $U$ B means everything in A and B, so,
A  $U$ B = {a, e, i, o, u, l. g, b, r } 
Hope this helped!

Answer 2

Ahh..this is sets topics - A U B = all the elements found in A and B. But do note, do not repeat the elements if it is the same. And if the question were to ask : n(AUB) = total number of elements found in A and B.