18. What is the interest rate of a 6-year, monthly $625 annuity due with a present value of $37,654?

19. After saving diligently her entire career, Terrence is ready to retire with a nest egg of $672,500. She needs to invest this money in a mix of stocks and bonds that will allow her to withdraw $5,850 per month for 20 years. What annual interest rate (APR) does she need to earn?

20. Bradley borrowed $72,500 in student loans and he has just graduated from Elon University. He earns enough at his new job to allow him to pay $575 per month on the loan. If the annual rate on the student loan is 4.38% (compounded monthly), how long will it take Bradley to pay off his student loans? Specify the number of months to the nearest whole number.