Let the time taken by Partha to cover 60km be x hours. As per the condition, Narayan will cover 60km in x−4 hours. Therefore, Speed of Partha =60/x And Speed of Narayan =60/(x−4) It is also given that Partha reaches the mid-point of A and B two hours before Narayan reaches B. Hence, ⇒
30
60
x
+2=
60
60
(x−4)
x
2
+2=x−4
x+4
2
=x−4 x+4=2x−8 x=12 OR Partha will take 12 hours to cross 60km. ⇒ Speed of Partha =60∕12=5Kmph