Beginner investor working as a silent partner

[Christina Williams]

Hi BP!

I'm new to REI and I'm working with a seasoned investor on a SFR flip so I can learn more. I am putting up about $50k into the flip as a silent partner and he said he's putting up about $30k into the flip. The only thing I'm unsure about is whether or not he's actually putting up $30k into the flip and not just saying that so he can make extra back. We bought the property for $400k, it is a SFR 3Bed 2.5Bath and 1730 sq ft. We're doing a full rehab on the property.

How do I make sure I'm getting my fair split of 50/50? What type of documentation and receipts or invoices do I ask for? We've already begun the process so I haven't gone to a lawyer to draw up any official agreements but we do have an agreement he created outlining the profit split. 

Any advice?

Thanks BP Community!!