An aerodynamic three-wheeled automobile (the dart) runs on compressed natural gas stored in two cylinders in the rear of the vehicle. The $13,000 dart can cruise at speeds up to 80 miles per hour, and it can travel 100 miles per gallon of fuel. Another two-seater automobile costs $10,000 and averages 50 miles per gallon of compressed natural gas. If fuel costs $8. 00 per gallon and marr is 10% and 15% per year, over what range of annual miles driven is the dart more economical? assume a useful life of five years for both cars.