document.write( "Question 1130665: Use two equations in two variables to solve the application. \r
\n" ); document.write( "\n" ); document.write( "With the wind, a plane can fly 2,700 miles in 5 hours. Against the same wind, the trip takes 6 hours. Find the airspeed of the plane (the speed in still air). \n" ); document.write( "

Algebra.Com's Answer #747271 by ikleyn(52794) $\"\"$ $\"About$

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document.write( "Let x be the airspeed of the plane (in miles per hour), and\r\n" );
document.write( "let y be the speed of the wind.\r\n" );
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document.write( "Then the effective speed of the plane flying with the wind is (x+y) miles per hour,\r\n" );
document.write( "while its speed flying against the wind is (x-y) mph.\r\n" );
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document.write( "From the condition, the effective speed with the wind is   = 540 mph.\r\n" );
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document.write( "The effective speed against the wind is   = 450 mph.\r\n" );
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document.write( "It gives you two equations\r\n" );
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document.write( "x + y = 540    (1)\r\n" );
document.write( "x - y = 450    (2)\r\n" );
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document.write( "To solve the system, add the equations. You will get\r\n" );
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document.write( "2x = 540+450 = 990  ====>  x = 990/2 = 495.\r\n" );
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document.write( "Answer.  The airspeed of the plane is  495 mph.\r\n" );
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