Let $\displaystyle {U}$ be the universal set, where:
$\displaystyle {U}={\left\lbrace{1},{2},{3},{4},{5},{6},{7},{8},{9}\right\rbrace}$ 
Let sets $\displaystyle {A}$ and $\displaystyle {B}$ be subsets of $\displaystyle {U}$, where:

$\displaystyle {A}={\left\lbrace{1},{5},{6},{8},{9}\right\rbrace}$ and $\displaystyle {B}={\left\lbrace{1},{3},{7},{9}\right\rbrace}$ 

Find $\displaystyle {\left({A}\cup{B}\right)}^{{c}}:{\lbrace}$  $\displaystyle {\rbrace}$ 

Find $\displaystyle {A}^{{c}}\cap{B}^{{c}}:{\lbrace}$ $\displaystyle {\rbrace}$ 

Enter the elements as a list, separated by commas with no spaces, in order from smallest to largest. If the result is the empty set, enter DNE

You may want to draw a Venn Diagram to help answer this question.