After that, I did one or two transactions per year, adding and subtracting rentals, and occasional flips & wholetales. 

Using the above steps you will start with todays ARV, haircut by 10-15%, subtract estimated rehab costs, subtract house flippers "other expenses", subtract your fee.

You get a quote from a contractor on what it would take to rehab the place and subtract that from your %70 rule 

After subtracting the $700,000 due on the mortgage note, the net net is $1.7 million.  

Same rule, just don't subtract any rehab costs 

You need to subtract all the variables, like Property management, Capital Expenditures, Repairs, Vacancy..  

Subtract out your debt service and you have your cash flow.

Plus, at those rents, you're actually losing money on the homes when you factor in R&M, taxes and insurance (after you subtract out the lot rent).2) Renovate and sell off the two vacant homes for whatever you can get, focusing on the $300 lot rent.3) You now have the following economics: 13 lots x $300 x 12 x .6 = $28,080 NOI.4) Your payment is roughly $2,000 per month P&I, as far as I can figure.

What I would do is take the value of the house after you repair it, multiply that by .7 then subtract the 12k.

Take the income above and subtract all the expenses.