Question

Solve for r: C = 2pir.

Answer 1

Okay so you want to get the r alone. You know how you would solve this problem: 10x = 20? You would multiply by 10 and get x = 2. Well, on this problem, you will actually divide by 2pi to get the r alone.
c/(2pi) = r

Answer 2

I mean divide by 10

Answer 3

do you get it?

Answer 4

C = 2[pi ]r
Divide both sides by 2[pi]
Hence, r = C/(2[pi])