Please show the excel formula

a. You have just made an offer on a new home and are seeking a mortgage. You need to borrow $400,000. The bank offers a 30-year mortgage with fixed monthly payments and an APR of 4.80%. Use the monthly compounding to compute interest. What is the amount of your monthly payment if you take this loan? b. How much will you owe on the mortgage after 2 years? After 2 years, your banker offers refinancing your mortgage at the APR of 4.50% with monthly payments for the remaining 28 years. If you accept this offer, you can borrow the remaining balance of your existing mortgage at this new rate. You can then pay off the existing one and move on to the new mortgage. If refinancing requires the document fee of $8,000, would you accept this offer? C