Mortgage DTI Calculation - Is my lender wrong?

[EDWARD M.]

I am currently applying for a loan. I'm not sure if my lender is calculating my DTI correctly. Please let me know if this is correct:

Gross Monthly Income: 6,000

Monthly Debt: 610

Rental Income: 1,300 * .75 = 975

PITI: 2800

DTI Limit: 43%

She is calculating it as (6,000+975)*43% = 2999.25

2999.25-610 = 2389.25

Is this correct? I think it should be 6,000*43% = 2580

2580 + 975 - 610 = 2945 ????

I did not think you could only use 43% of the rental income. Please if someone can help, I'm supposed to put in a best and final offer by tonight!