After a thorough research, there exists the same question that has the following choices.
A. 6.29
B. 12.57
C. 18.86
D. 25.13
The correct answer is letter B 12. 57
First, we need to get the circumference
C = 2pir
C = 12 pi
360/ 60+60 = 360/120 = 3
12 pi / 3 = 4 pi = 4 x 3.1415 = 12.57