A. A∩B=B∩A B.A∪B=B∪A C.A∪A=A D.B∩B=B E.A\B=B\A 15.If S={1,2,3,4,5,6,7} is the universal set ,P={1,2,3,4} and Q´={1,2,7}, then P∩Q=….. A. {1,2,3} B.{3,4} C.{3} D.{4} E.∅ 16.If P∪Q={x,y,z,u,v},P∩Q={z,u}