The areas of two spheres are 49 pi and 81 pi. The sum of their volumes is 11,792. What is the volume of the large sphere?
Assume that the radius of small one is r and the radius of the large one is R. Then their areas are
For small one, S1=4Pi*r^2
For large one, S2=4Pi*R^2
By hypothesis, ...
The solution is explained simply and with complete equations.