64x-541=-803
64x=-262
x=4.09375
48pi because the circumference is 18pi and that Times 3 is 48pi
The circumference of the circle is given by the following equation:
C=2πr, where r is the radius of the circle.
In your picture, the radius is just 3.5 mi.
Plug that in to the equation, and solve.
C=2π(3.5)
C=21.99 mi