Question

If U={1,3,5,7,11,13,17,19,23} and A={3,5,7,11} and B={3,11,13,23} and C={1,5,11,17} find:
A U (B∩C)

Answer 1

B={3,11,13,23} and C={1,5,11,17}

\(B \cap C\) represents the elements existing in both sets \(B\) and \(C\)

Answer 2

take a good look at sets B and C,
what are the elements that exist in both sets ?