2002 AMC 10A Problem 12

Mr. Earl E. Bird leaves his house for work at exactly $8{:}00$ A.M. every morning. When he averages $40$ miles per hour, he arrives at his workplace three minutes late. When he averages $60$ miles per hour, he arrives three minutes early. At what average speed, in miles per hour, should Mr. Bird drive to arrive at his workplace precisely on time?