document.write( "Question 1153877: Over a distance of 120 km , the average speed of a train 40 kmh faster than the speed of a car. If The train covers the distance in 30 minutes less time , find the speed of The train? \n" ); document.write( "

Algebra.Com's Answer #776186 by josgarithmetic(39620) $\"\"$ $\"About$

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document.write( "                   SPEED         TIME           DISTANCE\r\n" );
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document.write( "TRAIN              r+40          120/(r+40)       120\r\n" );
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document.write( "CAR                r             120/r            120\r\n" );
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document.write( "DIFFERENCE                      \r\n" );
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\n" ); document.write( "Thirty minutes is one-half hour.\r
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\n" ); document.write( "\n" ); document.write( "The train's time is less than car's time by half hour.\r
\n" ); document.write( "\n" ); document.write( " $\"120%2Fr-120%2F%28r%2B40%29=1%2F2\"$ .
\n" ); document.write( "Solve for r+40.
\n" ); document.write( "(But can be arranged differently.)\r
\n" ); document.write( "\n" ); document.write( "-\r
\n" ); document.write( "\n" ); document.write( " $\"240%2Fr-240%2F%28r%2B40%29=1\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"240%28r%2B40%29-240r=r%5E2%2B40r\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"240r%2B240%2A40-240r=r%5E2%2B40r\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"240%2A40=r%5E2%2B40r\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"r%5E2%2B40r-40%2A240=0\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"r%5E2%2B40r-9600=0\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"%28r-80%29%28r%2B120%29=0\"$ .\r
\n" ); document.write( "\n" ); document.write( ". \n" ); document.write( "

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