document.write( "Question 994774: A plane flies 435 miles in the wind and 345 miles against the wind in the same length of time. If the speed of the wind is 15 miles per hour, find the speed of the plane in still air \n" ); document.write( "

Algebra.Com's Answer #613789 by MathTherapy(10552) $\"\"$ $\"About$

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\n" ); document.write( "A plane flies 435 miles in the wind and 345 miles against the wind in the same length of time. If the speed of the wind is 15 miles per hour, find the speed of the plane in still air
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Let speed of the plane, in still air be S
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document.write( "Then speed of plane, with a tailwind = S + 15
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document.write( "Speed of plane, with a headwind = S – 15
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document.write( "We then form the following TIME equation: 
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document.write( "435(S - 15) = 345(S + 15) ------- Cross-multiplying
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document.write( "435S - 6,525 = 345S + 5,175
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document.write( "435S – 345S = 5,175 + 6,525
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document.write( "90S = 11,700
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document.write( "S, or speed of plane in still air = , or  mph \n" );
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