Basing on the data provided, if Bobby borrowed 500.00 and has an annual interest of 12% per year. 12% of the borrowed amount is equal to 60.00. Since he paid $680.00 that means that 680.00 – 500.00 = 180.00 worth of interest and since he pays an annual of 60.00 per year for the interest ergo, the answer is 3 years.