Question 583524
David and Frank cycle from  Islamabad to Murree, a distance of 210 km, at speeds of 20 km/hr and 15 km/hr respectively. David reaches Murree and starts back for Islamabad. How far from Murree will he meet Frank?


David speed = 20 km/h
distance = 210 km
time david = 210/20 = 10.5 hours

Frank speed = 15 km/h
In 10.5 hours he travels = 15*10.5 = 157.5 km

When David starts his return Frank has traveled 157.5

distance between them = 210 - 157.5 = 52.5 km

they are moving towards each other

add up speeds
15+20 = 35 km/h
distance = 52.5 km

time = 52.5 /35 =1.5 hours

David meets after 1.5 hours from Murree
David speed = 20 km/h
time = 1.5 hours

30 km from Murree.