Answer:
First, multiply the radius by 2 to get the diameter 18 inches. Then, multiply the diameter by 3.14 (an approximation for 1) to get a circumference of about 56.52 inches. If the diameter doubles the circumference doubles.
Step-by-step explanation:
18π = 56.52
36π = 113.04
56.52*2 = 113.04