A softball has a volume of 125/6πcubic inches. Find the radius of the softball.

They are both functions of the cube of the radius or even the cube of the diameter for that matter, since one is a linear function of the other.

V = (4/3) pi r^3

If you do volumes of both, the (4/3) and the pi cancel

Do ratios of r^3 Thats just an example