document.write( "Question 1125422: Please help me set this up and solve. Thank you so much.
\n" ); document.write( "Matt and Anna Killian are frequent fliers on​ Fast-n-Go Airlines. They often fly between two cities that are a distance of 1575 miles apart. On one particular​ trip, they flew into the wind and the trip took 4.5 hours. The return trip with the wind behind​ them, only took about 3.5 hours. Find the speed of the wind and the speed of the plane in still air.
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Algebra.Com's Answer #741744 by ikleyn(52790)\"\" \"About 
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document.write( "The airplane effective speed, when flying into a head wind, is  \"1575%2F4.5\" = 350 mph. \r\n" );
document.write( "This speed is the difference  u-v  of the airplane speed in still air and the wind speed:  u - v = 350 mph.\r\n" );
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document.write( "The airplane effective speed, when flying with the wind, is  \"1575%2F3.5\" = 450 mph.\r\n" );
document.write( "This speed is the sum u+v of the airplane speed in still air and the wind speed: u + v = 450 mph.\r\n" );
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document.write( "To determine the airplane speed in still air  \"u\"  and the wind speed  \"v\", you need to solve this system of two equations:\r\n" );
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document.write( "u - v = 350,   (1)\r\n" );
document.write( "u + v = 450.   (2)\r\n" );
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document.write( "Add the equations (1) and (2). You will get\r\n" );
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document.write( "2u = 350 + 450\r\n" );
document.write( "2u = 800,\r\n" );
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document.write( "u = \"800%2F2\" = 400 miles per hour.  It is the airplane speed in still air.\r\n" );
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document.write( "Then from (1) you find  v = u - 400 = 450 - 400 = 50 miles per hour.  It is the wind speed.\r\n" );
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\n" ); document.write( "\n" ); document.write( "It is a typical \"tailwind and headwind\" word problem.\r
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\n" ); document.write( "\n" ); document.write( "See the lessons \r
\n" ); document.write( "\n" ); document.write( "    - Wind and Current problems \r
\n" ); document.write( "\n" ); document.write( "    - Wind and Current problems solvable by quadratic equations \r
\n" ); document.write( "\n" ); document.write( "    - Selected problems from the archive on a plane flying with and against the wind \r
\n" ); document.write( "\n" ); document.write( "in this site, where you will find other similar solved problems with detailed explanations.\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
\n" ); document.write( "\n" ); document.write( "    ALGEBRA-I - YOUR ONLINE TEXTBOOK.\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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\n" ); document.write( "\n" ); document.write( "Save the link to this online textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-I
\n" ); document.write( "https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "to your archive and use it when it is needed.\r
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