Question

If the universal set U is defined by
U = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} and

A = {1, 2, 3, 4 }
B = {3, 4, 5, 6, 7}

What is n(A ∩ B) ?

Answer 1

what elements are in both A and B?

{3,4}