CFM through an orifice?

This is not school work.

CFM through orifice plate at given vacuum, air, I'm not worried about density but I'd assume 29.92 I have: Venturi flow 137.86 per SQ IN per 25 IN HG

I've also seen that an orifice is 60% as efficient as a venturi, but 60 sounds too round of a # I also don't know if square inch is right because an orifice plate should be a diameter.

I can work the problem to a known answer both by using a diameter and correcting by 60%, or by converting my diameter to square inches. and not correcting by 60%.

I need to know what orifice diameters will flow 50, 125, and 200 CFM.