The volume that is inside the larger cylinder shown but outside the cylinder with the smaller radius, r, can be found with the formula below.

V= 1,024π−16πr2

V is the volume inside the larger cylinder but outside the smaller cylinder in cubic centimeters. r is the radius of the smaller cylinder in centimeters.

Which equation and solution give the radius of the smaller cylinder if the volume inside the larger cylinder but outside the smaller cylinder is 768π centimeters3?