I think that C would be the best answer because you have to multiply and then divide.
Hi there!
The answer is

In this formula d represents the diameter.
We know that 2 times the radius equals the diameter, hence

Therefore we can replace the 2r in the original formula by d, and then we get the following:
Answer:
-13, 0.4,7 its the 4th one
Step-by-step explanation: