A, Band C all start their journey from the same place and all three follow the same route. However, A travels at a speed of 60 km/h, B at a speed of 75 km/h and C at a speed of 80 km/h. Also, A starts the journey five hours before B does. If B and C both overtake A at the same instance while travelling, how much time after A did C start the journey?

Correct option is C

Given:
Speed of A = 60 km/h
Speed of B = 75 km/h
Speed of C = 80 km/h
T(A) = T(B) + 5
T(A) = T(C) + h
Formula Used:
Distance = Speed x Time
Solution:
Let, t = time taken by B
The distance traveled is the same for A & B thus,
60 x (t + 5) = 75 x t
60t + 300 = 75t
15t = 300
t = 20
Distance traveled by B = 75 x 20 = 1500 km
Now,
For B & C, the distance is the same,
T(C) x 80 = 1500
T(C) = 75/4
In hours = 18 hours 45 minutes
Now, the Time taken by A = T(A) = t + 5 = 20 + 5 = 25 hours
So, h = difference between the time of A & C
T(A) = T(C) + h
h = T(A) - T(C) = 25 hours - 18 hours 45 minutes = 6 hours 15 minutes.