Question

write an expression which solves for the radius of an object having the circumference of 30 feet

Answer 1

C=2pi(r)
30=2pi (r)
r=(30)/(2pi)

Answer 2

$circumference=30ft.\\\\circumference=2\pi r\ (r-radius)\\\\2\pi r=30\ \ \ \ /:2\pi\\\\r=\frac{30}{2\pi}\\\\r=\frac{15}{\pi}\ (ft)\\\\\frac{15}{\pi}\approx\frac{15}{3.14}\approx4.78\ (ft)$