A passenger train left Austin, Texas, at 12:00pm bound for Dallas, exactly 210 miles away; it traveled at a steady 50 miles per hour.
At the same instant, a freight train left Dallas headed for Austin on the same track, traveling at 20 miles per hour.
At this same high noon, a fly leaped from the nose of the passenger train and flew along the track at 100 miles per hour. When the fly touched the nose of the oncoming freight train, she turned and flew back along the track at 100 miles per hour toward the passenger train.
When she reached the nose of the passenger train, she instantly turned and flew back toward the freight train. She continued turning and flying until, you guessed it, she was squashed as the trains collided head on. How far had the fly flown before her untimely demise?