If A,B and C are three subsets of a non-empty set X, then (A′∩B′∩C)∪(B∩C)∪(A∩C) is equal to
If A, B and C be three non empty sets given in such a way that A×B=A×C, then prove that B = C.
If A, B, C are three sets such that A⊂B, then prove that C−B⊂C−A