two trains 100 miles apart are approaching at 30 miles per hour.they will collide after 3.33 hrs. the speed of the faster must be less than 30mph, the speed of the slower greater than zero neglect not moving.the bird wings it for 3.33 hrs so travels 200 mi . 60 x3.33hrs.
example train A 20 mph, train B 10 mph. they aapproach each other at 10 plus 20 mph .train Atravels 67 mi B 33mi