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.
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
$B-A$
Let $A$ and $B$ be two sets in the universal set. Then $A - B$ equals
If $aN = \{ ax:x \in N\} $ and $bN \cap cN = dN$, where $b$, $c \in N$ are relatively prime, then
If $A=\{1,2,3,4\}, B=\{3,4,5,6\}, C=\{5,6,7,8\}$ and $D=\{7,8,9,10\} ;$ find
$B \cup C \cup D$