Answer:
1350 degrees
Explanation:
Using the formula (n-2)180, we can find out that the sum of all the angles of a dodecagon is 1800 degrees. We then divide that number by 12 to find the angle measure of one angle, giving us 150 degrees. To find the sum of 9 of them, multiply 150 with 9, giving up 1350 degrees. Hope this helped!