SOLUTION: the rate of a plane in calm air is 140 mph. flying with the wind, the plane can fly 450 miles in 2 hours less time than is required to make the return trip against the wind. find t

Question 447480: the rate of a plane in calm air is 140 mph. flying with the wind, the plane can fly 450 miles in 2 hours less time than is required to make the return trip against the wind. find the rate of the wind.
Answer by jorel1380(3719) (Show Source): You can put this solution on YOUR website!
450/(140+x)+2=450/(140-x)
450(140-x)+2(140+x)(140-x)=450(140+x)
63000-450x+39200-2x2=63000+450x
39200-900x-2x2=0
0=2x2+900x-39200
0=x2+450x-19600
(x+490)(x-40)=0
x=-490 or 40
Throwing out the negative answer, we get the wind speed to be 40 mph..

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