As Vince said it is a quick guideline and won't work in most places with current interest rates and house prices. 

I currently work in the turnkey investment world helping investors create a real estate portfolio, if you are ever interested in trading different strategies and goals, I'd love to connect! 

Would the banks still be intrested with me as I currently am unemployed?

With a low 4.75% rate but minimal cash flow ($50–$125/month), your equity could likely work harder elsewhere.

Foreclosures ar near all time lows.

Look, we’d all like to search the internet, find a deal for sale, analyze the property as having a great cash flow at current interest rates, with lots of upside potential in a gentrifying market.  

An 80% occupancy rate indicates low demand. 

The triplex is occupied and currently bringing in positive cash flow.

@Ram Go "Initial Debt" may or may not be the same thing as the current loan balance. 

I mostly work in low to moderate income areas anyway so it checks all those other boxes.