How to calculate ROI with multiple loans on purchase property?

[Ben O'Neill]

I recently purchased a duplex for $450,000 with 20% down. However I pulled $50,000 out of a 401k loan with a 10.5% interest rate to be part of the $90,000 down payment. The 10.5% interest on the 401k loan is likely higher than I would have been getting otherwise with no risk of downturn. How should I calculate the ROI considering I really only put $40,000 in the deal with out of pocket cash and my 401k loan is like a hard money loan on the side? Does Bigger Pockets have a calculator that can accommodate other loans that are part of a purchase transaction on top of the mortgage to calculate ROI? i.e. hard money, friend/family money, 401k loan. The 401k loan has a 5 year payback period so I'd really like to see the ROI with $40,000 down and 401k loan payments and mortgage payments running simultaneously.