Answer
a) A U B = { x| (x E A) V (x E B) } = { x| (x E B) V (x E A) } = B U A
b) A ∩ B = { x| (x E A) /\ (x E B) } = { x| (x E B) /\ (x E A) } = B ∩ A.
Work Step by Step
a) A U B means A union B. So x would be an element of A or B. Then use commutative law for logic OR, AND.
b) A ∩ B means the intersection of A and B. So x would be an element of both A and B. Then use commutative law for logic OR, AND.
