How do I solve the problem below?

You plan to buy a $100,000 home using a 30-year mortgage obtained from your local credit union. The mortgage rate offered to you is 8.25 percent. You will make a down payment of 20 percent of the purchase price.

1. Calculate your monthly payments on this mortgage.
2. Calculate the amount of interest and, separately, the principal paid in payment 25.
3. Calculate the amount of interest and, separately, the principal paid in payment 225.
4. Calculate the amount of interest paid over the life of this mortgage.