SOLUTION: A plane can fly 320 mph in still air. If it can fly 185 miles downwind in the same amount of time it can fly 135 miles upwind, find the velocity of the wind.

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Question 835576: A plane can fly 320 mph in still air. If it can fly 185 miles downwind in the same amount of time it can fly 135 miles upwind, find the velocity of the wind.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +w+ = the velocity of the wind
+320+%2B+w+ = the plane's speed flying downwind
+320+-+w+ = the plane's speed flying upwind
Let +t+ = the time in hours for either trip
---------------------------------------
Equation for flying downwind:
(1) +185+=+%28+320+%2B+w+%29%2At+
Equation for flying upwind:
(2) +135+=+%28+320+-+w+%29%2At+
------------------------
(1) +t+=+185+%2F+%28+320+%2B+w+%29+
and
(2) +t+=+135+%2F+%28+320+-+w+%29+
-------------------------
By substitution:
+185+%2F+%28+320+%2B+w+%29+=+135+%2F+%28+320+-+w+%29+
Multiply both sides by +%28+320+%2B+w+%29%2A%28+320+-+w+%29+
+185%2A%28+320+-+w+%29+=+135%2A%28+320+%2B+w+%29+
+59200+-+185w+=+43200+%2B+135w+
+320w+=+16000+
+w+=+50+
The wind speed is 50 mi/hr
check:
(1) +t+=+185+%2F+%28+320+%2B+50+%29+
(1) +t+=+185%2F370+
(1) +t+=+.5+ hrs
and
(2) +t+=+135+%2F+%28+320+-+50+%29+
(2) +t+=+135+%2F+270+
(2) +t+=+.5+ hrs
OK