SOLUTION: A plane can travel 1,015 miles in 7 hours against the wind. Traveling with the same wind, the plane can travel 820 miles in 4 hours. How fast can the plane travel in still air and

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: A plane can travel 1,015 miles in 7 hours against the wind. Traveling with the same wind, the plane can travel 820 miles in 4 hours. How fast can the plane travel in still air and       Log On


   

Question 1105239: A plane can travel 1,015 miles in 7 hours against the wind. Traveling with the same wind, the plane can travel 820 miles in 4 hours. How fast can the plane travel in still air and how fast is the wind current?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = the speed in mi/hr of the plane in still air
Let +c+ = the speed in mi/hr of the wind
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+s+-+c+=+1015%2F7+
+s+%2B+c+=+820%2F4+
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+s+-+c+=+145+
+s+%2B+c+=+205+
Add the equations
+2s+=+350+
+s+=+175+
and
+s+%2B+c+=+205+
+175+%2B+c+=+205+
+c+=+30+
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The speed of the plane in still air is 175 mi/hr
The speed of the wind is 30 mi/hr
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