Maybe it gets clearer if you compare the relative values of the 4 variables.w−y corresponds to the benfits of RXR, x−z also corresponds to the benefits of RXR. But maybe I was not precise enough: The equivalence does not follow only from w>x>y>z, we also need to take into account the definitions of the 4 variables. Do you see what I mean?
Maybe it gets clearer if you compare the relative values of the 4 variables.w−y corresponds to the benfits of RXR, x−z also corresponds to the benefits of RXR. But maybe I was not precise enough: The equivalence does not follow only from w>x>y>z, we also need to take into account the definitions of the 4 variables.
Do you see what I mean?