I have a Formula which suggests the Correct Win Wager Size to take advantage of the size of the Overlay.

( Market Odds/Rated Odds - 1 ) / Rated Odds

Sometimes the animal is well Under the assessed Rated Odds and therefore is not a betting proposition.

I wish to take advantage of the LAY betting at Betfair.
Could someone convert the above Formula so that it applies the exact same procedure for animals that are UnderLays?

I figure that now I am betting the animal will lose , so the LAY Rated Odds will be 100% minus the Rated Odds Percentage and then divide that into 100.

And I figure the Market Odds would be 100% minus the available Lay Odds Percentage divided into 100

If anyone ken what I am on about , am I right?

If anyone has some idea what I am after , could you please post the Formula?