The formula for the circumference is 2πr.
The diameter d is given, which is 2 times the radius r (d = 2r)
So you have to calculate π d = 3.142×1.8 ≈ 5.7
The answer is B, because the numbers in the equation are 2, and -3x. The signs have to stay with the numbers they are with. So if you move the 3 to the front you have to keep the negative with it.