Explanation:
You didn't include a diagram, but a dodecagon is a 12 sided polygon.
The SUM of the interior angles = (n-2) * 180 where n =12
(n-2)* 180
(12-2) * 180 = 1800 <====this is the SUM of the 12 interior angles
so EACH angle is 1800 / 12 = 150 degrees