Operating expenses calculation

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Ok lets say my i pay

100 in taxes

100 in insurance

80 in maintenance

Property manager 120

Hoa 100

Anual vacancy: 1,200

Anual : NOL 7,200

Rent: gross rent 14,400

So my operating expenses are 50%?

NOL 7,200 ÷ 14,400(gross rent) = 0.5 NOL

100 - 0.5NOL = 99.5 operating expenses

Im screwed up. I dont understand wich is one is correct.

Lets see other example

NOL15,643 ÷ 19,800 = 0.79 operating expenses. This example is correct and the other example is not correct or i dont know. Whats wrong with these calculations?