How to back into debt to income ratio

[crunchtime9999]

Hi,
I am making a calculator to back into a pre-defined debt to income ratio to refinance. I just can't figure out how to do this so any help would be appreciated.

I need to take the sume of d35 and d46 and subtract the amount needed to reach a pre-defined debt to income ratio (which I currently input into cell b53). The resulting reduction in expenses needs to populate in call d45.

I pasted a screenshot below to show what I need.

Thanks for all the help everyone. I know it's probably simple algebra.....but I have been out of school way to long.

Excel Workbook
	A	B	C	D
29	MONTHLY EXPENSES			HomeOwner
30	1. Installment payments ( min Pmt )			$600.00
31	2. Revolving payments ( min Pmt )			$0.00
32	3. Car payment(s)			$600.00
33	4. Existing Other Homes PITI			$0.00
34	5. Other			$0.00
35		Total Expenses		$1,200.00
36
37
38	CURRENT HOUSING EXPENSES			HomeOwner
39	1. Fully Amortized Pmt Principal Home			$3,000.00
40	2. Mortgage Insurance			$0.00
41	3. Property Taxes			$5,000.00
42	4. Hazard and Flood Insurance			$400.00
43	5. HOA/Condo Fees			$100.00
44	6. Other			$0.00
45	Amount you need to Reduce your Payment to Qual.
46		Total Expenses		$8,500.00
Loan Modification Calculator

 

[SamTYler]

Actual Income times Desired DTI = Desired Debt.
Actual debt - Desired Debt = Amount to reduce Actual Debt

With actual Income in "D27"

=SUM(D35, D46)-(D27*B53)

 

[crunchtime9999]

Sam,
Thank you. I tried this and is says it's a circular reference and does not back into the correct number. Am I doing something wrong?

 

[crunchtime9999]

Sam,
I got it now. I removed the sum of the minus amount and just input a formula and it works beautiful now.

Thanks so much for the assist. I appreciate it.

 

[SamTYler]

I removed the sum of the minus amount

Uh... there is no sum of the minus amount.

Sum the two expenses.

Subtract the product of income and desired CTI from the total expenses.

The result of the subtraction is the amount you need to reduce expenses to meet desired DTI.