Hello from MrBillDoesMath!
Answer:
3.14
Discussion:
C = circumference, r = radius, d = diameter = 2 r
For a circle, C = 2 Pi r = d Pi
Substituting the values in the question gives
C = d Pi
28.26 = 9 Pi => divide both sides by 9
Pi = 28.26/9 = 3.14
Thank you,
MrB