Question 1031838
An airplane flies 250 km against the wind and 680 km with the wind in a total time of 4 hour. The speed of the airplane is 300 km/h. What is the speed of the wind? 
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a = plane's airspeed = 300
w = windspeed
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250/(300-w) + 680/(300+w) = 4
250*(300+w) + 680*(300-w) = 4*(300+w)*(300-w) = 360000 - 4w^2
75000 + 204000 - 430w = 360000 - 4w^2
4w^2 - 430w - 81000 = 0
*[invoke solve_quadratic_equation 4,-430,-81000]
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w =~ 206 km/hr
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No fun flying upwind like that.
Downwind is great.