6. (3.5 Points) Twenty years ago, you bought a house and took out a 30 year, $300,000 mortgage. Your fixed interest rate on this mortgage is 5.25% (which was the appropriate risk-adjusted rate when you obtained the mortgage). You now have the opportunity to refinance the unpaid loan balance with a new 10-year loan. The interest rate on this new loan will be 4.75% and you must pay a $4,000 upfront fee to complete this transaction. A. What is your unpaid loan balance (on the original mortgage) after you have lived in the house for 20 years, and made all 240 payments on time? B. If you refinance, how much will you save each month with the new 10-year mortgage? C. Should you refinance the mortgage if you plan to live in the house for 10 more years? D. Would your decision change if you refinanced with a new 15-year mortgage with the same (new) 4.75% annual interest rate and the same upfront costs of $4,000? Why or why not