Answer:

Step-by-step explanation:
Given

Required
Evaluate when n = 12
Substitute 12 for n in 

Simplify the fraction


Well...it says the sum of the angles measure 360...so lets set them equal to 360
40 + x - 10 + 1/3x + x - 20 = 360...combine like terms
2 1/3x + 10 = 360
7/3x = 360 - 10
7/3x = 350
x = 350/(7/3)
x = 350 * 3/7
x = 1050/7
x = 150 <=====
Just a question, are the 2's squares?
Answer:
A
Step-by-step explanation:
Brainliest PLEASE