Question

one external angle of a regular polygon is 18 degree what is the sum of its external angle how many sides does it have what is the sum of its internal angles

Answer 1

to find how many side it has
360/18
20
it is a 20 sided polygon
the sum of its interior angle is 360 degree

Answer 2

sum of external angles is equal to 360°. number of sides is equal to 360/18=20 sum of internal angles is equal to 360°