Coastline,
Do you mean this guy will be working by himself and only taking 30% of what he cleans?
Or do you mean, he'll be working along side you and taking 30% of what you both clean?
If it's the first one, it sounds very little and he'll be working his socks off to make a living; then it'll be a matter of time before he 'jacks it all in' and goes back to factory work or somthing. I think you'd be better paying him 70%.