Question

The density of the Earth, at any distance r from its center, is approximately (14.2-11.6(r/R)*10^3) Kg/m^3, where R is the radius of the Earth. Show that this density leads to a moment of inertia I = 0.330MR2 about an axis through the center, where M is the mass of the Earth.

I really do not even know where to start here, any help would be appreciated
Ayano Bari Areri
answer