SOLUTION: a plane flies 720 mi against a steady 30 mi/h headwind and then returns to the same point with the wind. if the entire trip takes 10 h what is the planes speed in still air?

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Question 26927: a plane flies 720 mi against a steady 30 mi/h headwind and then returns to the same point with the wind. if the entire trip takes 10 h what is the planes speed in still air?
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
720%2F%28x%2B30%29%2B720%2F%28x-30%29=10
720[(x+30)+(x-30)]=10[(x+30)(x-30)]
720%282x%29=10%28x%5E2-900%29
1440x-21600=10x%5E2-900
10x%5E2-1440x-9000=0
x%5E2-144-900=0
Factor:
(x+6) and (x-150)
Remove the negative x=150

Hence, the speed of the plane in still ari is 150mph.
Paul.