Answer
9 (nonagon)
Work Step by Step
Using the equation for exterior angles, we find:
$$\frac{360}{n}=\frac{360}{n+1}+4 \\ \frac{360}{n}n(n+1)=\frac{360}{n+1}n(n+1)+4n(n+1) \\ n=9,-10$$
Since n is positive, it follows that there is 9 sides, which is a nonagon.
