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An airplane makes a 990 km flight with a tailwind and returns, flying into the same wind.The total flying time is 3 hrs 20 mins and the airplanes speed in still air is 600 km/h what is the speed of the wind?

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What have you tried? You must have tried something since you thought to tag the question "quadratics". Please explain that. Where do you get stuck? – Henning Makholm Sep 28 '12 at 14:11

Suppose the speed of the wind is $x$ km/hr. Then the airplane speeds during upwind and downwind are $600+x$ and $600-x$, respectively. Then $$ \frac{990}{600+x} + \frac{990}{600-x} = 3\frac{1}{3}$$

Solve it and you will have $x = 60$ km/hr.

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