@Paul Feijoo The reason for the big discrepancy is that the math in the “example story” is wrong.It goes wrong in the third paragraph where it says “They end up paying their mortgage for 3 months before selling the home, which amounts to $40,800 (8 percent of $170,000 = $13,600 x 3 months).”Whoever wrote this story incorrectly calculated the interest for 3 months as $40,800.

You both responded to that incorrectly as I did not say no one wants to do it on their own or anything about doing it all for yourself.

Saying 'no' to pets will drastically reduce your candidate pool, so you might shop for a pet-friendly house (hard floors, securely fenced yard).Even if you're cool with pets, you should meet the specific pets and have a good long talk with the candidate on that animal's temperament and quirks prior to agreeing to lease to them.

I don't know if its correct or incorrect, but here goes: Let’s just say I bought a single family home for $30,000 and the repair amount is $10,000, then that means the total amount I invested so far is $40,000.

I made an incorrect assumption.

I think your terminology is incorrect here.

Even great pets have accidents or quirks.  

Your rents are incorrect.

You do not need to be an expert on the topic and in fact if you are incorrect, you could be held liable for someone else's decision that was based on the information you gave them if they are harmed in some way as a result of that decision.

I'm either calculating incorrectly or I have to dig deep to find them.