document.write( "Question 1143190: Danilo drove from his home in valenzuela a distance of 40 miles and then returned again on the same highway the round trip took 2hrs. His speed on the return trip was 30 miles per hour faster than his speed in going.What was his rate of speed on the trip from his home
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Algebra.Com's Answer #763988 by ikleyn(52802) $\"\"$ $\"About$

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document.write( "Let x = his rate on the trip from his home, in miles per hour (which is the unknown value under the question).\r\n" );
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document.write( "Then his rate on the way back is (x+30) mph.\r\n" );
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document.write( "The time spent for the trip \"to there\" is    hours.\r\n" );
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document.write( "The time spent for the trip back is    hours.\r\n" );
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document.write( "The total time is 2 hours, which gives you this \"time\" equation\r\n" );
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document.write( "     +  = 2   hours.\r\n" );
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document.write( "To solve it, multiply both sides by  x*(x+30). You will get\r\n" );
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document.write( "    40*(x+30) + 40x = 2x*(x+30),\r\n" );
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document.write( "    40x + 1200 + 40x = 2x^2 + 60x\r\n" );
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document.write( "    2x^2 - 20x - 1200 = 0\r\n" );
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document.write( "    x^2  - 10x - 600  = 0\r\n" );
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document.write( "    (x-30)*(x+20) = 0\r\n" );
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document.write( "There are two roots,  x= 30  and x= -20,  but only positive  x= 30 makes sense.\r\n" );
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document.write( "ANSWER.  His rate \"to there\" is  30 mph.\r\n" );
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document.write( "CHECK.   +  =  +  =  +  = 2 hours.    ! Correct !\r\n" );
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\n" ); document.write( "\n" ); document.write( "Using \"time\" equation is the STANDARD method of solving such problems.\r
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\n" ); document.write( "\n" ); document.write( "It is simple, logical, straightforward and economic. Going in this way, you will not make a mistake - the logic of the method
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\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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