A: 25.12 (26 if your rounding)
B: You have to multiply R by 2 then by pi (3.14)
C: 10.5 (11 if your rounding)
Explanation:
For a: A circle's circumference is its diameter multiplied by pi (3.14) To get the diameter you would multiple the radius by 2. Therefore your answer being 25.12 (Round to 26 if you want)
For c: Divide 65 by pi then that answer by two.