Decagon angle

I beilive I have heard that  a decagon equals 1440 degree's what you can do lets see you have 9 angles degree mesaurments on here add them then subtract the sum from 1440 after that your diffrence will be your answer..... 

like this 

$156 + 178 + 124 +132 +138+142+116+178 +159 = sum$

$1440 - sum = difference$

$Difference = answer.$

The formula for the sum of the angles of an n-gon (in this case, a 10-gon), is 180(n - 2). So, the sum of the angles is 1440. Now, we just calculate 1440 - (156 + 178 + 124 + 132 + 138 + 142 + 116 + 178 + 159) = 1440 - 1323 = 117.

Hoping this helped,

asdf334