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
$A-B$
Let $A=\{1,2,3,4,5,6\}, B=\{2,4,6,8\} .$ Find $A-B$ and $B-A$
If $A = \{ x:x$ is a natural number $\} ,B = \{ x:x$ is an even natural number $\} $ $C = \{ x:x$ is an odd natural number $\} $ and $D = \{ x:x$ is a prime number $\} ,$ find
$A \cap B$
Find sets $A, B$ and $C$ such that $A \cap B, B \cap C$ and $A \cap C$ are non-empty sets and $A \cap B \cap C=\varnothing$
State whether each of the following statement is true or false. Justify you answer.
$\{2,6,10,14\}$ and $\{3,7,11,15\}$ are disjoint sets.