Any help to my current dilemma would be gratefully received.

I have the following scenario:

Profit Odds
Horse A -66.26 1.70
Horse B +48.73 1.86
Horse C +82.73 11.50
Horse D +6.73 7.00
Horse E -47.27 18.00

I have to work out what the next bet on each horse would be so that the profit is equal for each and every horse. The problem is they are all interdependent so when I bet 20 on horse A it reduces the profit on all the other horses by 20 (Horse B becomes 28.73, Horse C 62.73 etc). As a result I keep going round in circles.

I thought this would be easy but I am stuck. Can anyone point me in the right direction.
Many Thanks,
Scott