Let $A$ and $B$ be two sets in the universal set. Then $A - B$ equals
If $n(A) = 3$, $n(B) = 6$ and $A \subseteq B$. Then the number of elements in $A \cup B$ is equal to
If $A=\{3,6,9,12,15,18,21\}, B=\{4,8,12,16,20\},$ $C=\{2,4,6,8,10,12,14,16\}, D=\{5,10,15,20\} ;$ find
$A-C$
State whether each of the following statement is true or false. Justify you answer.
$\{a, e, i, o, u\}$ and $\{a, b, c, d\}$ are disjoint sets.
Show that the following four conditions are equivalent:
$(i)A \subset B\,\,\,({\rm{ ii }})A - B = \phi \quad (iii)A \cup B = B\quad (iv)A \cap B = A$