Question

A motor boat goes downstream in a river and covers the
distance between two ports in 4 hours. It covers this
distance upstream in 6 hours. If the speed of the stream
is 4 km/h, find the speed of the boat in still water.​

Answer 1

I hope this clears it all up.

Answer 2

Answer:

First downstream-

speed = 4km/hr

time= 4hrs

so, 4(x+4)km

Now upstream-

speed = 4km/hr

time= 6hrs

so, 6(x-4)

We have to find speed of boat

so, 4(x+4) = 6(x-4)

4x+16 = 6x-24

16+24 = 6x-4x

40 = 2x

40/2 = x

20 = x

so speed in still water is 20km/hr