Each exterior angle of a regular polygon measures 20. how many sides does the polygon have? a.20 b.18 c.15 d.16

We know that
The sum of exterior angles of any polygon is 360 degrees. 
Each exterior angle of a regular polygon = 360/n
 where n is the number of sides. 
So
n = 360/20 = 18

the answer is the option
b.18 

However, if the workers do outside of what's normally expected, go ahead and tip.

21/2 or 5/2