A cantilever beam AB having rectangular cross sections with constant width and varying height hx is subjected

Question:

A cantilever beam AB having rectangular cross sections with constant width and varying height hx is subjected to a uniform load of intensity (see figure).
How should the height hx vary as a function of (measured from the free end of the beam) in order to have a fully stressed beam? (Express hx in terms of the height hB at the fixed end of the beam.)