I am planning on buying a car in three years. I expect that the price of the model that I want will be $20,000 at that time. I have an investment account in a bank. My plan is to invest some money today and then add $100 each month into this account starting next month. I am expecting to earn 0.6% per month (7.2% APR) from my investments. In order to have $20,000 in 3 years, how much should I invest today (in addition to my monthly savings/investments)?