Police use the formula r = 2645-05-10-00-00_files/i0200000.jpg to approximate the rate of speed in miles per hour of a vehicle from its skid marks, where L is the length of the skid marks in feet. About how fast is a car going that leaves skid marks of 80 ft? a. 30 mi/h c. 50 mi/h b. 40 mi/h d. 60 mi/h