Question:
Let $A$ and $B$ be two sets in the same universal set. Then, $A-B=$
(a) $A \cap B$
(b) $A^{\prime} \cap B$
(c) $A \cap B^{\prime}$
(d) none of these.
Solution:
(c) $A \cap B^{\prime}$
$A-B$ belongs to those elements of $A$ that do not belong to $B$.
$\therefore A-B=A \cap B^{\prime}$