Question

Elmer's new car gives 50 percent better fuel efficiency, measured in kilometers per liter, than his old car. However, his new car uses diesel fuel, which is 20% more expensive per liter than the gasoline his old car used. By what percent will elmer save money if he uses his new car instead of his old car for a long trip?

Answer 1

let earlier mileage ; 5km/l

price; 2 $

so cost per liter ; 2.25

new mileage ; 7.5 km/l

and price ; 2.4$

new cost per litr ; 3.125

so saving % ; 3.125-2.5/3.125 ; 20 %

Hope it helps you....