Back of the napkin...IRR would be better. 

If not try and dig up that "old napkin" or try to use the hand shake agreement that he gave you the home!  

It has partnered with the Loading Dock to accept reusable building materials at two of its facilities: The Eastern Sanitary Landfill in White Marsh and the Central Acceptance Facility in Cockeysville.

Well You should be able to do the math on a bar napkin to be an investor .

@Clinton Ide There is a quick "back of the napkin" formula to evaluate a park that will usually tell you if the deal is worth a closer look.

Your lease should state that the unit is to be kept in a clean and sanitary condition.

@Ken Primrose the quickest, back of the napkin way of analyzing a deal is by using the 50% rule.

From a back of the napkin analysis (and not knowing the area or the specifics of this project), a purchase of $75k, rehab of $30k and exit at $155k, it has enough room to continue with your due diligence to confirm numbers.Do NOT rely on Prop Stream for values, get actual comps and walk the comps, look at all photos of the comps and compare finishes.

There is a back of the napkin formula in flipping that is essentially (purchase + repairs) < 70% of ARV.

My lease specifies that she has to maintain a sanitary and habitable condition for the property, however you define that.