Originally Posted by nick1024

It depends of what you want. If you aim for a fixed revenue, you can do this:

odds	bet
100x	3*n
50x	6*n
30x	10*n
20x	15*n
10x	30*n

So, you'll always get a revenue of 300*n (n, whatever integer multiplier). And you'll spend 64*n tropical cocktails.

Originally Posted by HungryHunter

kay, just bet 20 on each and I get "64?"

I shouldn't drop out of high school LOL

If your n = 1, you'll be betting:

3 on the 100x return boat
6 on the 50x return boat
10 on the 30x return boat
15 on the 20x return boat
30 on the 10x return boat

Doing this it will get you a guaranteed 300 cocktails as a reward by spending 64 (3+6+10+15+30) pearls for the bets.
For higher n values, you'll get 600 for 128, 900 for 192, 1200 for 256 and so on.