1. A business that owns or leases 10 or more vehicles may qualify for auto manufacturer fleet purchase incentive. Incentives very from $300 to $7000 on new vehicles. In August 2003, the manufacturer's fleet incentive for a 2004 Chevrolet Cavalier was $1,400. An auto dealer offers an additional discount to fleet buyers who purchase one or more new Cavaliers. To encourage sales, the dealer reduces the after-incentive price of each car by x%, where x is the total number of cars purchased. Assuming that the pre-incentive price of a 2004 Chevrolet Cavalier is$14,400, how many vehicles would the dealer need to sell in order to maximize revenue?