Answer:
45
Step-by-step explanation:
The sum of interior angles in a triangle is equal to 180
2x - 12 + 2x + 17 + 9x - 7 = 180 add like terms
13x - 2 = 180 add 2 to both sides
13x = 182 divide both side by 13
x = 14
m<X = 2x + 17 replace x with 14
2*14 + 17 = 45
To find this just put 8 over 20 because that is how many red pieces there are divide the equation and you will get 0.4 so I would say the answer is A.
Total = 21 feet
if each is 3 feet
21/3 = 7
Therefore, there are 7 sections
the height:

(with g being the gravitational acceleration)