SOLUTION: Please help with the following word problem! A plane flies 390 mph in still air. It makes a round trip of 5040 miles in a total of 13 hours, one way with the jet stream and the

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Question 285441: Please help with the following word problem!
A plane flies 390 mph in still air. It makes a round trip of 5040 miles in a total of 13 hours, one way with the jet stream and the other way against the jet stream. Find the speed of the jet stream.


I know that Rate X Time = Distance, so using J for jet stream and T for time, I tried (390-J) X (T) = 2520 (1/2 the distance since it was round-trip) and (390+J) X (13-T) = 2520. I also tried (390-J) X (T) = (390+J) X (13-T).
I get to a point where I'm not sure what to do with two variables. How would you set this problem up? If I am on the right track, how do I solve for 2 variables?
Thank you so much!
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
2520/(390 + J) + 2520/(390-J) = 13
2520*(390-J) + 2520*(390+J) = 13(390-J)(390+J)
A quadratic in J
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