document.write( "Question 1138064: Two cars traveled from Elmhurst to Oakville, a distance of 100 miles. One car traveled 10 mph faster than the other and arrived 5/6 of an hour sooner. Find the speed of the faster car. \n" ); document.write( "

Algebra.Com's Answer #755948 by ikleyn(53765) $\"\"$ $\"About$

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document.write( "Let x = the speed of the faster car, in mph\r\n" );
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document.write( "Then the speed of the slower car is (x-10) miles per hour.\r\n" );
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document.write( "From the condition, you have this \"time\" equation\r\n" );
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document.write( "     -  =    of an hour\r\n" );
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document.write( "To solve it, multiply both sides by  6x*(x-1).  You will get\r\n" );
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document.write( "    600*x - 600*(x-10) = 5x*(x-10).\r\n" );
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document.write( "    6000 = 5x^2 - 50x\r\n" );
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document.write( "    5x^2 - 50x - 6000 = 0\r\n" );
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document.write( "    x^2 - 10x - 1200 = 0\r\n" );
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document.write( "    (x-40)*(x+30) = 0.\r\n" );
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document.write( "The roots are 40 and -30.  Only positive root is meaningful.\r\n" );
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document.write( "ANSWER.  The faster car speed is 40 mph.\r\n" );
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document.write( "CHECK.   The faster car spends   =   hours.\r\n" );
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document.write( "         The slower car spends   =   hours.\r\n" );
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document.write( "         The difference is   =  =  =  of an hour.   ! Correct !\r\n" );
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\n" ); document.write( "\n" ); document.write( "From my post learn on how to write, to solve and to use the \"time\" equation.\r
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