13. Finance The formula for simple interest is I = prt, where I is the interest, p is the principal, r is the interest rate per year, and t is the time in years.
a. You invest $550 for three years. Find the amount of simple interest you earn
with an annual interest rate of 4.5%.
b. Suppose you invested $900 for two years. You earned $67.50 in simple
interest. What was the annual rate of interest?
c. You invest $812 with an annual interest rate of 6.5%. You earned $316.68 in
simple interest. For how many years was the money invested?