Answer: 180 is the sum of the tringles
Step-by-step explanation:
2x+7x+11x=180
20x=180
x=9
Now you should put the the value of x to get the angles
2x=2x9=18
7x=7x9=63
11x=11x9=99
Now to double check add all of them together
99+18+63=180
Hoped I helped!
