Try this option: 1. Rule for the sum of interior angles is: S=180°(n-2), where n - numbers of sides of n-gon. 2. using the formula shown above: 7 - 180*11=1980 8 - 180*16=2880 9 - 180*30=5400° 10 - 180*33=5940 11 - 180*5=900 12 - 180*24=4320 13 - 180*8=1440° 14 - 180*21=3780
