Rubina started her journey by car at 16:50 hours and finished at 21:15 hours on the same day. The total time taken to complete the journey is:

Rohan walks around a circular field at the rate of 1 round per hour while Shreyas runs around it at the rate of 5 rounds per hour. They start in the same direction from the same point at 8:30 AM. When will they first cross each other?

In covering 90 km, R takes 4 hours more than S. If R triples his speed, then he would take 2 hours less than S. What is R's original speed (in km/h)?