The speed of a boat when travelling downstream is 32 km/h, whereas when travelling upstream it is 28 km/h. What is the speed of the boat in still water?

Ans.  Suppose the speed of boat in still water is x km/h and speed of stream is y km/h

Speedof boat in downstream = (x + y) km/h x+ y = 32 …(i) 

Speed of boat in upstream = (x – y) km/h

x – y = 28 …(ii)

Add. Eqs. (i) and (ii), we get 2x = 60

x = 30 km/h