Given $n(U) = 20$, $n(A) = 12$, $n(B) = 9$, $n(A \cap B) = 4$, where $U$ is the universal set, $A$ and $B$ are subsets of $U$, then $n({(A \cup B)^C}) = $

Taking the set of natural numbers as the universal set, write down the complements of the following sets:

$\{ x:x$ is an even natural number $\} $

Let $U=\{1,2,3,4,5,6,7,8,9\}, A=\{1,2,3,4\}, B=\{2,4,6,8\}$ and $C=\{3,4,5,6\} .$ Find

$\left(A^{\prime}\right)^{\prime}$

If $U=\{a, b, c, d, e, f, g, h\},$ find the complements of the following sets:

$D=\{f, g, h, a\}$

Fill in the blanks to make each of the following a true statement :

$A \cap A^{\prime}=\ldots$

If $U =\{1,2,3,4,5,6,7,8,9\}, A =\{2,4,6,8\}$ and $B =\{2,3,5,7\} .$ Verify that

$(A \cup B)^{\prime}=A^{\prime} \cap B^{\prime}$