Engineering Finance problem

1. A person lends $2000 for five years at 10% per annum simple interest; then the entire proceeds are invested for 10 years at 9% per year, compounded annually. How much money will the person have at the end of the entire 15-year period

2. What is the present value of $10 000 to be received 20 years from now, if the principal is invested at 8% per year, compounded annually

3. Find the principal of a loan in which the interest rate is 1% per month, payable monthly, and in which the borrower has just made the first monthly interest payment of $50