A recent newspaper advertisement offered car buyers the opportunity to lease a new vehicle for $5,000 down plus $350 per month for 48 months. At the end of the 48 months, the car will be returned to the dealer. Alternatively, the same car could be purchased outright for $34,000. It is estimated that in 48 months, the car could be sold for $20,000. At what interest rate (compounded monthly) are these two options equivalent?