Jack's Jumpin' Junk Joint has a 5.64% APR mortgage on his shop, which has a remaining balance of $203,044.90. The loan has 9.25 more years (111 payments) of $2,351.89 per month until the current mortgage will be paid off. Interest is a tax-deductible expense for Jack, and Jack's tax rate is 28%. Jack can refinance the mortgage with a 4.68% APR 15-year mortgage for a total after-tax cost to refinance of $7,245. What is Jack's net advantage to refunding (NA) to refinance the mortgage, to the nearest dollar?

NOTE: The mortgages are installment loans (not like bonds, which are interest-only loans), so you cannot simply plug values into Equation (20.4) to get the correct answer. Instead, this situation is just like a home mortgage.