Question

Wanna be a brainliest.....answer dis

a boat goes 12 km upstream and 40 km downstream in 8hrs. it can go 16km upstream and 32 km downstream in the same tym. find speed of the boatin still water and speed off stream...?

Answer 1

Let the speed of boat in still water be x km/h.
Let the speed of stream be y km/h.

The speed of the boat upstream = x-y
The speed of the boat downstream = x+y

$since \: time = \frac{distance}{time} \\ \\ therefore \: 8 = \frac{12}{x - y} + \frac{40}{x + y} \\ \\ and \: 8 = \frac{16}{x - y} + \frac{32}{x + y} \\ \\ suppose \frac{1}{x - y} = p \: \: and \\ \: \frac{1}{x + y} = q$
So, the equation becomes
8 = 12p + 40q
8 = 16p + 32q

Now, solve the equations for p and q by elimination method and replace p by x-y and q by x+y.

You get
x-y = 4
x+y= 8

Solve these equations for x and y by elimination method. So the speed of the boat in still water is 6 km/hr and the speed of the stream is 2 km/hr.

$hope \: it \: helps \: you.$
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Answer 2

Hope it helps!!!!!!!!!!!!!!