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## #1 2013-08-24 16:47:31

shivusuja
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### linear equation in two variable

A BOAT CAN TRAVEL15km/hr IN STILL WATER MOVES AT DISTANCE 30KM UPSTREAM AND SAME THE DOWN STREAM IN 4hr 30 min . FIND THE SPEED OF STREAM.

## #2 2013-08-24 17:07:12

bob bundy
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### Re: linear equation in two variable

hi shivusuja

When travelling  downstream the boat will move (relative to the land) at a velocity 15 + v where v is the velocity of the stream.

And upstream at a velocity 15 - v

So you can use

in the two cases using 30 for the distance and v for the velocity of the stream.

Get the time for each, add them and set that equal to 4.5 to find v

Bob

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

## #3 2013-08-24 20:34:10

shivusuja
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### Re: linear equation in two variable

The Sum Is To Be Done In Two Variables[x,y]

## #4 2013-08-25 04:22:43

bob bundy
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### Re: linear equation in two variable

That seems to make the question unnecessarily complicated but OK, you could do this:

Let t be the time for the upstream journey.

Then (4.5 - t)  is the time for the downstream journey.

Now you have two variables, t and v.

Same method, just takes longer, as the first step is to eliminate t.

Bob

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei