<checks the 19/31 through y = (-0.6*20/19)x + 1; nods>

<nods with realisation at the selected x=y=19/31 point corresponding to a different location in the true depiction>

(Assuming that it stays on the line of 'what is possible', in any case a higher Y than otherwise, but finding it then according to the constant X--1 - ((19/31) * (1/19)), 30/31, yes...)

I confess I do not understand the significance of the terms mixed outcome and weighted sum in this context, I do not see how the numbers 11/31 and 20/31 have been obtained, and I do not presently see how the same effect can apply in the second situation in which the relative positions of the symmetric point and its (Pareto?) lines have not been shifted, but I now see how in the first situation the point selected can be favourable for Y! (This representing convincing of the underlying concept that I was doubtrful of.) Thank you very much for the time taken to explain this to me!