I'm tying to work out how much to stake in order to collect a set amount.

I want to make $20 profit

the odds for the 3 bets are

$2.25
$4.80
$5.50

hope some one can help?

wait not quite what you want.

Do 1/(odds) for each selection

So you would get a total of 0.834 across the 3 selections.

That's a profit of 16.6%.

To make $20 you di $20/0.166 = 120.48

Take the individual percentages and times them by 120.48 and you have your figures:

a)53.54
b)25.10
c)21.90


Make sense ?

Thanks