Two runners start running together for a certain distance, one at 5 km/h and another at 8 km/h. The former arrives one and a half an hour before the latter. The distance in Km is -

Question: Two runners start running together for a certain distance, one at 5 km/h and another at 8 km/h. The former arrives one and a half an hour before the latter. The distance in Km is -

Solution:
Let the distance be = P
time of the first runner = P/5 hour
second runner = P/8

ATQ,
P/5 - P/8 = 3/2
3P/40 = 3/2
3P = 60
P = 20 km