Answer: 107 meters
Explanation:
There are 2 ways to solve this:
1. The formula for arc length is: arc length = angle (in radians) * radius.
Thus, convert 123 degrees to radians by multiplying it by (pi/180), and then multiply this number by 50 (half of the diameter is the radius) in order to get 107.
2. Find the circumference of the track using C = pi*diameter and get 314.16. Then, set up a proportion: 314.16 meters / 360 degrees = x meters / 123 degrees and solve to get 107 :)