It depends on what type of polygon it is and how many angles it has.
1260
The interior angles of a polygon are (number of side -2)*180 = sum of angles
1440 degrees
1440 degrees
7
6
8
15
1800 degrees
3240
The polygon will have 12 equal sides and each interior angle measures 150 degrees.
There is no regular polygon with an interior angle of 20o. If the interior angle is 120o then there are six sides and the sum of the angles is 720o.