A boat goes 44 km downstream and 30 km upstream in 10 hours. The same boat can go 40 km upstream and 55 km downstream in 13 hours. Find the speed (in km/hr) of the boat in still water.

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)?