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

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

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

$\{ x:x$ is a natural number divisible by $ 3 $ and $5\} $

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

${{\mathop{\rm U}\nolimits} ^\prime } \cap A =  \ldots $

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

$A=\{a, b, c\}$

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

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

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

$C=\{a, c, e, g\}$