A man drives to a town at an average speed of 60 mph. He returns by a road which is 10 miles shorter, at an average speed of 45 mph. The return trip takes him the same time as the first trip. Find the length of each road.

v1= 60mph -> d1

v2= 45 mph -> d2= d1-10 

v= d/ t -> v1= d1/t -> 60= d1/t

                v2= d2/t -> 45= d1-10/t 

-> d1/ 60= (d1- 10 )/45 ->  3d1= 4d1- 40->  40 = d1 ->

                                                                       d2= 30