Question

If 2 sets a b are having 43 elements in common

Answer 1

if 2 sets A and B are having 43 elements in common ,then the number of elements common to each of the sets A*B AND B*A would be 43 X 43 as you can choose 43 elements which are common to both A and B in 43 ways separately in both the sets and when you will multiply these, you will get the same answer.