document.write( "Question 86024: During rush hour, Adriana can drive 40 miles using the side roads in the same time that it takes to travel 20 miles on the freeway. If Adriana's rate on the side roads is 9mi/h faster than her rate on the freeway, find her rate on the side roads. \r
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Algebra.Com's Answer #62172 by Edwin McCravy(20054) $\"\"$ $\"About$

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During rush hour, Adriana can drive 40 miles using the side roads in the same time that it takes to travel 20 miles on the freeway. If Adriana's rate on the side roads is 9mi/h faster than her rate on the freeway, find her rate on the side roads.
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document.write( "No, it's 18 mph.  You can think out the answer without algebra.  She can go\r\n" );
document.write( "twice as fasr on the side roads as on the freeway, and the only way \"twice as\r\n" );
document.write( "fast\" can be \"9 mph faster\" is for the slower rate to be 9 mph and the faster\r\n" );
document.write( "rate to be 18 mph. \r\n" );
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document.write( "But here's the algebraic way:\r\n" );
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document.write( "Make this chart:\r\n" );
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document.write( "             DISTANCE       RATE     TIME\r\n" );
document.write( "Side roads                                          \r\n" );
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document.write( "Freeway                                         \r\n" );
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document.write( "Fill in the distances:\r\n" );
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document.write( "             DISTANCE       RATE     TIME\r\n" );
document.write( "Side roads     40                                   \r\n" );
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document.write( "Freeway        20                               \r\n" );
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document.write( "Let the rate on the Freeway be x.  Then the rate on the\r\n" );
document.write( "side roads is x+9. Fill those in\r\n" );
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document.write( "             DISTANCE       RATE     TIME\r\n" );
document.write( "Side roads     40           x+9                   \r\n" );
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document.write( "Freeway        20            x                   \r\n" );
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document.write( "Now fill in the times by using \r\n" );
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document.write( "             DISTANCE       RATE     TIME\r\n" );
document.write( "Side roads     40           x+9     \r\n" );
document.write( "Freeway        20            x       \r\n" );
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document.write( "The times are equal so now we have\r\n" );
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document.write( "               = \r\n" );
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document.write( "Can you solve that? If not post again asking how.\r\n" );
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document.write( "Solution:  x = 9, that is 9 mph on the freeway and 18 mph\r\n" );
document.write( "on the side roads.\r\n" );
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