The formula s = √21d relates a stunt car’s speed s in miles per hour at the beginning of a skid to the length d of the skid in feet. A stunt driver must skid her car to a stop just in front of a wall. When the driver starts her skid 200 feet from the wall, she is traveling at 64 mph. When the driver comes to a stop, how many feet will be between her car and the wall? Round to the nearest foot.