Prove that for any two sets A and B,,A'-B'=B-A

Question

I want the solution of this question

Answer 1

Let U = the Universal Set.  By definition:

 

A' = U - A

B' = U - B

 

A' - B' = (U - A) - (U - B)

A' - B' = U - A - U + B

A' - B' = B - A