Read thru the thread for the 40% --- it was a reply to you.
Capital development expense is not equity. I am not talking about return on equity. Land value is irrelevant. Marginal has the same meaning as in marginal tax bracket.
I believe Treit quoted Solomon as saying that the payback time for fish farms is 2.5 years. That's the source of the 40% ROI. Maybe he asked S last September on the tour?