## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$8$
$A$ and $B$ means the elements are both in $A$ and $B$. The intersection of two sets is the set of elements that are in both sets. Add all the numbers in regions that are comon to $A$ and $B$. Using the diagram: $n(A\cap B)=3+5=8$