Combined, my girlfriend and I should have enough for a duplex within the next couple months, but we hit a roadblock.

I’ve been struggling trying to find out how to find monthly interest and principal payments separately but I kept coming up with  them combined which made it difficult for me figure out how much equity I would accumulate in 1 year on my first investment property.I found this formula on YouTube and it seems to be helpful. 

I would combine @Steve Morris and @Andrea Weule into one and that would about cover it for me. 

You are now looking a combined tax structure of $970,000 due to that one asset.

That is a great point.We are going to use a combination of such and use flips to fund the investing part of our plan. 

And the 1st probably still needs extra money to be brought current to avoid foreclosure.If a seller has equity and is motivated to sell there's probably some way to make a deal work, but I'm not sure I would personally combine a seller financed 2nd mortgage with also having the former owner stay in the property as a tenant.I guess it comes down to #s though, whether it makes sense.

You DEFINITELY want to try to buy this park as that will give you a 52 space park when you combine them -- that's far more valuable than a 30 and a 22 separately.

That usually involves some combination of grading, foundation drains, and waterproofing on the exterior of the foundation.

Any time you have a lot of folks and alcohol combined you can bet on shenanigans.

Meaning, it is a combination of the investor personal money (his equity injection) and the money he borrows.