Question

A man rows to a place 35 km in distant and back in 10 hours 30 minutes

Answer 1

Let speed of man and stream of 'V', 'U'.
Time 5÷V+U = 4÷V-U(Travelling distance in same time.)
5V-5U = 4V+4U
>> 5V-4V = 4U+5V >> 1V = 9U
>> V÷U = 9÷1.
Let U= x, V= 9x.
35÷2x (1÷5+1÷4) = 21÷2 >> 5÷x × 9÷20=3
>> 4x= 9÷3 >> x= 3÷4 >> x= 0.75 km/h.
Speed of stream = 1 × 0.75 = 0.75 km/h.

Hope you have got.