There are also many online calculators you can use if you do a search for them.

That would be called the BRRRR strategy - there is endless info on that strategy here and on the podcasts and in the BP bookstore.

Then they make a **** load of money on them, and still collect on loans  which they never make (plus interest). 

I was able to figure out that they had come upon some hard times and were significantly low on cash.

That is me reading between the lines, and I would suggest partnering with someone who has the money.

Additionally, not all transaction types support Locations, meaning you'll have to create journal entries to correct them—requiring a solid understanding of debits and credits, which can be time-consuming and error-prone.Instead, I recommend biting the bullet and upgrading to QuickBooks Online Plus for each entity.

On the other hand, what if you get hit with a slow year and have $0 profit?

Any advice on what I should do to retrieve January’s rent? 

New to real estate investing and looking for other perspectives on getting starting. 

They love the idea of wealth, financial freedom, but don't want to put their own financials on the line.