2 years ago a woman leased a new car by putting $2,000 down and signing a 48 month lease at $500 per month. She has received a letter from the lease company saying that she can complete the lease right now by making a single $10,000 payment and keep the car for 2 more years; or she can finish the lease by making the remaining 24 monthly payments of $500. Assuming that this customer can earn 6% by investing in Treasury securities, and ignoring any tax consequences, to determine the best option, the method to be used is: