Mike's grandmother opened a savings account in Mike's name and deposited some money into the account. The account pays an annual simple interest rate of 8%. After 12 years, the interest earned on the account was $7,680. How much money did Mike's grandmother deposit in the account?
For this problem, we can assume the total money is X, than we can get the equation of: 0.08*X*12=7680, than we can know X=8000, therefore, Mike's grandmother deposit 8000 in the account.
