document.write( "Question 1092475: Two planes fly in opposite directions. One travels 450
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Algebra.Com's Answer #707078 by ikleyn(53765) $\"\"$ $\"About$

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document.write( "Let t be the time under the question, in hours.\r\n" );
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document.write( "Then the first   plane will cover the distance  450*t miles in t hour,\r\n" );
document.write( "while the second plane will cover the distance  550*t miles in t hour.\r\n" );
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document.write( "Since they fly in opposite directions, the distance between them in t hours will be \r\n" );
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document.write( "450*t + 550*t.\r\n" );
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document.write( "According to the condition, the distance is 4000 miles. It gives an equation\r\n" );
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document.write( "450*t + 550*t = 4000.\r\n" );
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document.write( "Simplify and solve for t:\r\n" );
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document.write( "(450+550)*t = 4000 ====>  1000*t = 4000  ====>  t =  = 4 hours.\r\n" );
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document.write( "Answer.  It will take 4 hours.\r\n" );
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document.write( "Since their relative speed is 450 km/h + 550 km/h, the distance between the planes increases at the rate (450 + 550) = 1000 km/h.\r\n" );
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document.write( "Now apply the formula  t =  =  = 4 hours.\r\n" );
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document.write( "You get the same answer.\r\n" );
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\n" ); document.write( "\n" ); document.write( "See the lessons \r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this textbook under the section \"Word problems\", the topic \"Travel and Distance problems\".\r
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