Well then you take the $900 and multiply it by 12 to give you a year's total income and then subtract your yearly fees from that which is generally about 35%  (10%-Management, 5%-Maintenance, 5%-Vacancy, 15%- Insurance & Taxes.).

From there, you could take a line of credit or be refinancing to pull cash out and then really come up with a plan for that cash to multiply it through flipping, buying, rehabbing and raising rents, etc. 

Im $140,000 in debtNOI:  $6,944.00Cash on Cash ROI:17.56%Monthly Cashflow:$439.09Income-Expense Ratio (2% Rule):1.96%Total Initial Equity:$94,000.00Gross Rent Multiplier:1.89Debt Coverage Ratio:4.15Purchase Cap Rate:27.78%Pro Forma Cap Rate:5.79%

You'll need to determine your current DTI with the following formula: monthly income divided by 12, and multiply that by .45 (you'll really get a lenders attention by knowing this ahead of time, and come off much more professional). 

Is 0.75 multiply against what is charged for rent for the month or is multiply to the cash flow I get after I subtract all expenses such as insurance, taxes, and paying the existing home mortgage?

He was immediately on the phone with two neighbors accross the street with pickup trucks and yes he was out the same day, signed the agreement with keys returned and then I gave him the cash.For you, you could project the cost per day in rents not received multiplied by the amount of days he will be there with the court date & Sherriff serving the eviction and offer the tenant a percentage of that cash in his face and see if he takes the money and runs, freeing up the apartment.

Is 0.75 multiply against what is charged for rent for the month or is multiply to the cash flow I get after I subtract all expenses such as insurance, taxes, and paying the existing home mortgage?

Where it really adds up (multiplies) is with appreciation, depreciation, and mortgage pay down.

@Bryson Gilbert take the total sqft and multiply it by $35/ $40 ( this is how we do it in Texas).

@Jeegar Patel it's not exact, of course, but I usually just take the primary residence taxes and multiply them by 3.5 in Richland County where I buy my properties.