SOLUTION: Ben and Peter start off together on a 20km hike. Ben walks 4 times as fast as Peter, and when he comes to the end of the hike he turns around and walks back to meet Peter. How far,

Led "d" be the distance covered by Peter;  Then the distance covered by Ben is   (20 + (20-d)) = 40-d kilometers.


The sum of the distances they covered before they met each other was  d + (40-d) = 40 kilometers.


Since they spent equal time from the start to the meeting point, Ben covered 4 times the distance covered by Peter.


So we have


    d + 4d = 40 km;


Hence, the distance, covered by Peter is    of 40 kilometers, i.e. 8 kilometers.   ANSWER