Task: Question Answering
Input (English): Problem: on a certain date, pat invested $ 10,000 at x percent annual interest, compounded annually. if the total value of the investment plus interest at the end of 12 years will be $ 40,000, in how many years, the total value of the investment plus interest will increase to $ 160,000 ?
Options: a. 15, b. 16, c. 18, d. 20, e. 24
Output (English): e