I need someone to explain to me how we get the "amount of interest".

You plan to purchase an $50,000 house using a 15-year mortgage obtained from your local bank. The mortgage rate offered to you is 7.5 percent. You will make a down payment of 10 percent of the purchase price.

a.

Calculate your monthly payments on this mortgage. (Do not round intermediate calculations. Round your answer to 2 decimal places. (e.g., 32.16))

Monthly payment $

b.

Calculate the amount of interest and, separately, principal paid in the 120th payment. (Do not round intermediate calculations. Round your answers to 2 decimal places. (e.g., 32.16))

Amount of interest $ Amount of principal $