(a) If $A=\{1,2,3,4\}, B=\{2,4,5,8\}, C=\{3,4,5,6,7\}$, find
(i) $B \cup C$,
(ii) $A \cap B$, (iii) $A-C$.
(b) Let $S=\{a, b, c, d, e\}$ be the Universal set and let $A=\{a, b, d\}$ and $B\{b, d, e\}$ be two of its subsets. Find $(A \cap B)^{\prime}$ and $(A \cup B)^{\prime}$.