Find the value of a. Enter a numeric answer only.

Solution
For this case we have the following, the sum of the angles needs to be 360 since we have a circumference:
10a-4 +6a-2 +8a+6=360
Regrouping we have:
10a +6a +8a -4 -2 +6= 360
24a= 360
a= 360/24= 15