Moving 6/7 of its usual speed a train is 10 min late. Find its usual time to cover the journey.

New speed = 6/7 of usual speed
Now, time taken = 7/6 of usual time
(7/6 of the usual time) - (usual time) = 10 min
⇒ 1/6 of the usual time = 10 min
∴ Usual time = 60 min