What is the exterior and interior angle of a 18 sided polygon

Would assume the Polygon is an 18 sided regular polygon.

Exterior angle for regular polygon = 360/n      (Sum of angles of exterior angles = 360°)

where n = number of sides.

Exterior angle = 360 / 18 = 20

Exterior angle = 20°

Sum of exterior angle + Interior angle = 180°    (Both angles are on a straight line, so the sum is 180°)

Interior angle = 180° - 20°

Interior angle = 160°

Hope this explains it.