A pebble is stuck in a bicycle tyre. As the tire turns it leaves a mark on every 69 inch. How would u calculate the circumference?

1-Circumference is equal to the diameter times pi. The diameter is twice the radius. So r=9 then d=18. 18 times pi is 56.55 or 18pi.

2-23pi

3-16 times 2 is 32. so 32pi is your answer.

1 - C=20.5 the diameter would be C/pi so 20.5/pi = 6.53 so the radius would be 3.265.

1-203.08

2-1.97 (these are the same as the one above)

1-it would be 69 inches