document.write( "Question 545202: Assume that a plane is flying at a constant speed under
\n" ); document.write( "unvarying wind conditions. Traveling against a head
\n" ); document.write( "wind, it takes the plane 4 hours to travel 1540 miles.
\n" ); document.write( "Traveling with a tail wind, the plane flies 1365 miles in 3
\n" ); document.write( "hours. Find the speed of the plane and the speed of the
\n" ); document.write( "wind. \n" ); document.write( "

Algebra.Com's Answer #355530 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"w\"$ = wind speed
\n" ); document.write( "Let $\"s\"$ = speed of plane with no wind
\n" ); document.write( " $\"+s+-+w+\"$ = plane's speed against wind
\n" ); document.write( " $\"+s+%2B+w+\"$ = plane's speed with the wind
\n" ); document.write( "----------
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+1540+=+%28+s+-+w+%29%2A4+\"$
\n" ); document.write( "(2) $\"+1365+=+%28+s+%2B+w+%29%2A3+\"$
\n" ); document.write( "-------------------
\n" ); document.write( "(1) $\"+1540+=++4s+-+4w++\"$
\n" ); document.write( "(2) $\"+1365+=++3s+%2B+3w+\"$
\n" ); document.write( "Divide both sides of (1) by $\"4\"$ and
\n" ); document.write( "divide both sides of (2) by $\"3\"$
\n" ); document.write( "Then add the equations
\n" ); document.write( "(1) $\"+385+=+s+-+w+\"$
\n" ); document.write( "(2) $\"+455+=+s+%2B+w+\"$
\n" ); document.write( " $\"+2s+=+840+\"$
\n" ); document.write( " $\"+s+=+420+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+385+=+s+-+w+\"$
\n" ); document.write( "(1) $\"+385+=+420+-+w+\"$
\n" ); document.write( "(1) $\"+w+=+420+-+385+\"$
\n" ); document.write( "(1) $\"+w+=+35+\"$
\n" ); document.write( "the plane's speed in still air is 420 mi/hr
\n" ); document.write( "The wind's speed is 35 mi/hr
\n" ); document.write( "check:
\n" ); document.write( "(1) $\"+1540+=+%28+s+-+w+%29%2A4+\"$
\n" ); document.write( "(1) $\"+1540+=+%28+420+-+35+%29%2A4+\"$
\n" ); document.write( "(1) $\"+1540+=+385%2A4+\"$
\n" ); document.write( "(1) $\"+1540+=+1540+\"$
\n" ); document.write( "OK \n" ); document.write( "

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