#### Answer

(A∪B∪C)'= { }

#### Work Step by Step

U={1,2,3,4,5,6,7}
A={1,3,5,7}
B={1,2,3}
C={2,3,4,5,6}
TO FIND (A∪B∪C)' Let's first find A∪B∪C
A∪B∪C={1,3,5,7} ∪ {1,2,3} ∪ {2,3,4,5,6} = {1,2,3,4,5,6,7}
(All the elements of A and the elements of B that are not in A and elements of C which are not in A & B)
(A∪B∪C)'= { }
(All the elements of universal set U which are not there in (A∪B∪C))