SOLUTION: Against the wind a commercial airline in South America flew 340 miles in 2.5 hours With a tailwind the return trip took 2 hours. What was the speed of the airplane in still air? Wh

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Question 720825: Against the wind a commercial airline in South America flew 340 miles in 2.5 hours With a tailwind the return trip took 2 hours. What was the speed of the airplane in still air? What was the speed of the wind? thank you for answering!!!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
let +s+ = the speed of the plane in still air in mi/hr
Let +w+ = the wind speed in mi/hr
+s+%2B+w+ = the speed of the plane flying with the wind in mi/hr
+s+-+w+ = the speed of the plane flying against the wind in mi/hr
----------------
given:
Flying against the wind:
(1) +340+=+%28+s+-+w+%29%2A2.5+
Fly with the wind:
(2) +340+=+%28+s+%2B+w+%29%2A2+
-----------------------
(1) +2.5s++-+2.5w+=+340+
and
(2) +2s+%2B+2w+=+340+
---------------------
(1) +25s+-+25w+=+3400+
(1) +s+-+w+=+136+
and
(2) +s+%2B+w+=+170+
--------------------
Add (1) and (2)
+2s+=+306+
+s+=+153+
and, since
(2) +s+%2B+w+=+170+
(2) +153+%2B+w+=+170+
(2) +w+=+17+
The speed of the plane in still air is 153 mi/hr
The wind speed is 17 mi/hr
-------------
check:
(1) +340+=+%28+s+-+w+%29%2A2.5+
(1) +340+=+%28+153+-+17+%29%2A2.5+
(1) +340+=+136%2A2.5+
(1) +340+=+340+
OK
(2) +340+=+%28+s+%2B+w+%29%2A2+
(2) +340+=+%28+153+%2B+17+%29%2A2+
(2) +340+=+170%2A2+
(2) +340+=+340+
OK