Thanks Beton
So
94% Book value based on those prices.

If Fav wins = +8.00

If 2nd Fav wins = -$12.00

If 3rd Fav wins = -$7.72

If 4th fav wins = -$6.00

If all fall over = +$28.00

The O/L total ($40) has to be greater than the individual Liability ($30)

Alternatively
One could total the O/L for the 2nd-4th fav = $20.28

$20.28 divided by the 1st favs price $2.50 = O/L $8.11

$8.11 win bet on Fav.

+$2.16 Prof if fav wins.

This also keeps the Liab down by -$4.00 on each of the 2nd-4th favs
(as above) if they should get up to win race, rather than the original Beton example.

Well done Beton
A very interesting perspective .
Thanks for sharing your findings.

__________________
Cheers.