We have that the sides of the polygon is mathematically given as
n=20
Option C
From the question we are told
A regular polygon has possible angles of rotational symmetry of 20°, 40°, and 80°.
How many sides does the polygon have? 10 12 18 20
Arithmetic
Generally the equation for the Polygon exterior angle is mathematically given as
[tex]\theta=\frac{360}{n}\\\\18=\frac{390}{18}[/tex]
n=20
OptionC
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