The figure above shows part of a circle whose circumference is 45. If arcs of length 2 and length b continue to alternate around the entire circle so that there are 18 arcs of each length, what is the degree measure of each of the arcs of length b?
You know that 18(2 + b) = 45, so you can calculate b:
18(2 + b) = 45
36 + 18b = 45
18b = 9
b = 0.5
Now all you need to do to find the degree measure of an arc of length b is set up a ratio, like you do for LOTS of circle problems.