Same profit each day: v[(x-1)1.1 -x] = v[(y-1)1.1 - (y-1)] =v[(z-2)1.1 - (z-1)],
and from this I think x=z-1. y=z-2
Your formulas for the three days profits are correct. Maybe tried to skip too many steps in getting to relationship between x, y, and z?
v[(y-1)1.1 - (y-1)]
v[(z-2)1.1 - (z-1)]
I think you are golden otherwise.