If the property/market is good enough to arbitrage, it's good enough for the owner of the property to cut you out of the equation and do it himself (or have a family member do it).

Looking at a LOC from a family friend and trying to figure out how to approach the interest part of the equation. 

Somehow, someone started applying it to RE, and the whole thing equated to a bad game of telephone.Throw it out.  

Get the other 2 Realtors out of the equation.

When you throw a motivated seller into the equation sometimes it's even at a pretty steep discount.

Thank you for the feedback so far, I actually think I figured out the general formula and equations using a mortgage calculator.

The financial equation works out better than a 1% rule as it comes in at a 1.1-1.2 %  rent to cost of building and the apartment is brand new so you wouldn't expect any initial CAPEX. 

Not sure what college debt may do to this equation tho. 

Math is math, and if you have good numbers and plug them in, the resulting figure will tell you all you need to know; nearly everything about a rental property is quantifiable, even if you have to use estimates rather than hard facts in some parts of the equation. 

So even the best mortgage rates, in simple terms, equate to around 75% to 90% interest or more over time.