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

$C-A$

Find the union of each of the following pairs of sets :

$A=\{1,2,3\}, B=\varnothing$

If $A=\{1,2,3,4\}, B=\{3,4,5,6\}, C=\{5,6,7,8\}$ and $D=\{7,8,9,10\} ;$ find

$A \cup C$

Let $A$ and $B$ be two sets such that $n(A) = 0.16,\,n(B) = 0.14,\,n(A \cup B) = 0.25$. Then $n(A \cap B)$ is equal to

If $A$ and $B$ are not disjoint sets, then $n(A \cup B)$ is equal to

If $A, B$ and $C$ are three sets such that  $A \cap B = A \cap C$ and $A \cup B = A \cup C$ then