How to split ownership with varying initial investment.

[Nicholas Katsandoins]

I am hopefully soon to purchase a duplex at 400K. I will put down the 15% down payment and my partner (who I have because I need one in order to get a loan due to debt to income ratio) will put down nothing. I have heard a few different perspectives but looking for more. 

1) Upon selling take my 60K and then split everything else 50/50 

2) Based on debt taken and money put down between us (~40:60), take percentage of income or loss for everything. So any income would me split 40:60, any repair would be paid (40:60) etc. 

I would appreciate any other perspective or validation of ideas.