A Spherical Balloon with Radius $r$ Inches Has Volume $4 \frac{\pi r^{3}}{3}$

Short Answer

A spherical balloon with radius $r$ inches has volume $4 \frac{\pi r^{3}}{3}$ .
Find a function that represents the amount of air required to inflate the balloon from a radius of $4 \frac{\pi r^{3}}{3}$ inches to a radius of $r+3$ inches.