A car drives downhill with the speed of 90 m/h. On a level road, the same car goes 72 m/h, and uphill it goes "only" 60 m/h.

It takes this car 5 hours to go from town **A** to town **B**. The return trip only takes 4 hours.

Find the distance between the two towns.

the existing relation between the three speeds:

1/60+1/90=2/72

makes the solution independent of the uphill and downhill distribution and therefore we can assume a flat roat of length d and an average speed of 72:

2*d=9*72 ==> d=9*36= 324

ady