How do you sell a piece of yourself/stake?

[bmwnick1]

I hope this is the right place for the thread. I was wondering how to sell a piece of yourself. For example, if someone pays 10% of your buy in to a MTT, what percent of your winnings do they get? If they pay 100% of your buy in, its called a stake and they should get 50% right? so if they pay 10%, shouldn't they get 5%?