I calculated the annualized return using the equation for simple interest(multiplied 5.6% by 52/3,) your calculation considered the interest to be compounded.

I want to generate multiply streams of income from the land and the extra building.

I have been looking at the Gross Rent Multipliers (GRM) for only duplexes in Nashville-Davidson County dating back to March-2015. 

I am a big fan of the rent multiplier i.e. 1% per month etc.  

Or, multiply the mortgage by 1.25.

In order to break even, it has to have a GRM of 6 at the time, meaning I take the annual rent, multiply it by 6, that's the price where I can break even.

This strategy multiplies it's effectiveness if your working with a hard money lender that will work with wholesalers and pre-approve your deals for hard money lending.

But speaking in generalities, flipping will be the quickest way to multiply your cash, which I then personally would take to a value add multifamily deal.

Car not is 5 %my school loan is 4My wife’s is 6I am following the avalanche method , and starting off with an initial snow ball off 559.I just started budgeting this month so that snowball will increase once the dust settles. 

Personally I like to try and determine how many man hours things might take and then multiply that by what a standard labor rate might be.