Question

find the measure of each exterior angle in a 17-gon

Answer 1

exterior angle is always 360
$\frac{360}{17} = 21.1764705882$
hence 21.2 (3s.f.)

Answer 2

The interior angle is a regular polygon is equal to 180-360/n, where n is the number of sides.
For a 17-sided regular polygon, 180-360/n is approximately 158.824 degrees.