V =
√
20
L
v
=
20
L

to estimate the speed of a car,
v
v
, in miles per hour, based on the length,
L
L
, in feet, of its skid marks 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 168 feet long. Approximately how fast was the car traveling? Round your answer to the nearest tenth (one decimal place) of a unit.