Police use the formulaV(Ll)=20L to estimate the speed of a car in miles per hour, based on the length,L, in feet, of its skidmarks when suddenly braking on a dry, asphalt road.

At the scene of an accident, a police officer measures a car's skid marks to be 115 feet long. Approximately how fast was the car traveling?_______________

One of the people involved in the accident says that he was traveling 54 mph when he braked. How long in feet should his car's skid marks be?____________