Question

If A and B are finite sets such that A ⊂ B, then n (A ∪ B) = ______.

Answer 1

If A and B are finite sets such that A ⊂ B, then n (A ∪ B) = n(B).

Explanation:

A ⊂ B 

⇒ A ∪ B = B

⇒ n(A ∪ B) = n(B)