document.write( "Question 1149792: Jon recently drove to visit his parents who live 60 miles away. On his way there his average speed was 9 miles per hour faster than on his way home (he ran into some bad weather). If Jon spent a total of 3 hours driving, find the two rates. \n" ); document.write( "

Algebra.Com's Answer #771135 by ikleyn(52803) $\"\"$ $\"About$

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document.write( "If x is the slower rate (in miles per hour), then the faster rate is (x+9) mph.\r\n" );
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document.write( "The \"time\" equation is\r\n" );
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document.write( "     +  = 3  hours.\r\n" );
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document.write( "Simplify\r\n" );
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document.write( "     +  = 1\r\n" );
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document.write( "then multiply both sides by x*(x+9)\r\n" );
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document.write( "    20*(x+9) + 20x = x*(x+9)\r\n" );
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document.write( "    20x + 180 + 20x = x^2 + 9x\r\n" );
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document.write( "    x^2 - 31x - 180 = 0\r\n" );
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document.write( "     =  =  = .\r\n" );
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document.write( "Only positive root makes sense  x =  = 36.\r\n" );
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document.write( "Answer.  The slower rate is 36 mph;  the faster rate is  36+9 = 45 mph.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Using \"time\" equation is the STANDARD method of solving such problems.\r
\n" ); document.write( "\n" ); document.write( "From this lesson, learn on how to write, how to use and how to solve a \"time\" equation.\r
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\n" ); document.write( "\n" ); document.write( "To see many other similar solved problems, look into the lessons\r
\n" ); document.write( "\n" ); document.write( "    - Had a car move faster it would arrive sooner\r
\n" ); document.write( "\n" ); document.write( "    - How far do you live from school? \r
\n" ); document.write( "\n" ); document.write( "    - Earthquake waves \r
\n" ); document.write( "\n" ); document.write( "    - Time equation: HOW TO use, HOW TO write and HOW TO solve it \r
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