A man takes 5 hours 45 min. in walking to a certain place and riding back. He would have gained 2 hours by riding both ways. The time he would take to walk both ways, is:
Let the distance be x km.
(Time taken to walk x km) + (Time taken to ride x km) = (23/4)hrs
=> (Time taken to walk 2x km) + (Time taken to ride 2x km) =(23/2)h
But, time taken to ride 2x km = (15/4) hrs Time taken to walk 2x km =[(23/2) - (15/4)] hrs = (31/4) hrs = 7 hrs 45 min.