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.
(In reply to Answer
by K Sengupta)
During The onward journey, let the respective distance (in miles)
traveled uphill, level and downhill be P, Q and R.
Then it follows that, during the return journey, the respective distance traveled uphill, level and downhill are R, Q and P.
Accordingly, by conditions of the problem:
P/60 + Q/72 + R/90 = 5
P/90 + Q/72 + R/60 = 4
Adding, we obtain:
(P+Q+R)/36 = 9, giving:
P+Q+R = 324
Consequently, the distance between the two towns is 324 miles.