given the following

Question

U = {1, 2, 3, 4, 5, 6, 7}

A = {1, 2, 4, 5}

B = {1, 3, 5, 7}

How many elements are in A ∩ B ?

Answer 1

∩ This symbol is for intersection, which means the elements are are in both A and B

A ∩ B = {1,5} so there are 2 elements in the set.