Figure out what value you bring to the equation that can't be easily replicated by googling someone else and try to justify an equity percentage around that. 

I find a lot of comfort in knowing that there is a concrete way of valuing a property by use of mathematical equations.

I’m currently in contract with a 4 plex that equates to a 2% or better rule and trying to be very conservative with maintenance and cap ex and it seems it would barely cash flow.This also includes 10% management since I’m long distance and using 100% financing on a 20 year note.

This does not always equate to a bad arrangement being that some agents working in intermediary statuses are quite honest.

As you gain experience you will turn the stories into a math equation and it either works or it doesn't.

No one financing 75% is getting that when all other factors are entered into the equation. 

Make sure you pay yourself (or company) in this equation, or the numbers just won't make sense.

is there an equation?

You can equate your goals to the horizon.

Putting money down to improve cash flow doesn’t alter the equation.