Two metal spheres (one with radius x cm and the other with radius x+7 cm) will be melted together to create a new single sphere. Express the radius, R, of the new sphere as a function of x.

In your question where as two metal sphere will be melted together to create a new single sphere and the radius is express as R of the new sphere function x and the answer is 4/3 * pi * (x^3 + (x+7) ^3) = 4/3 * pi * R^3