ATQ, Let the downstream speed of the boat and speed of the boat in still water be 8x km/hr and 7x km/hr, respectively. Therefore, speed of the stream = downstream speed - speed of the boat in still water Speed of stream Speed of stream = 8x−7x = x km/hr And, upstream speed of the boat = speed of the boat in still water - speed of stream Upstream speed Upstream speed=7x − x = 6x km/hr Given: 
So, downstream speed of the boat: 8x = 8×5 = 40km/hr Required time: 
