Been working on this for hours!!! Ive honestly given this problem 3 or more hours to no avail. "An irregularly shaped chunk of concrete has a hollow spherical cavity inside. The mass of the chunk is 38 kg, and the volume enclosed by the outside surface of the chunk is 0.025 m3. What is the radius of the spherical cavity?" This is what I have set up which is not working: density of concrete = M / (Voutside surface - Vcavity) what's wrong with that?? thankkks!!