document.write( "Question 837774: At 6 A.M. a snowplow, traveling at a constant speed, begins to clear a highway leading out of town. At 8 A.M. an automobile begins traveling the highway at a speed of 35 mi/hr and reaches the plow 20 minutes later. Find the speed of the snowplow. \n" ); document.write( "

Algebra.Com's Answer #504742 by Edwin McCravy(20060) $\"\"$ $\"About$

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At 6 A.M. a snowplow, traveling at a constant speed, begins to clear a highway leading out of town. At 8 A.M. an automobile begins traveling the highway at a speed of 35 mi/hr and reaches the plow 20 minutes later. Find the speed of the snowplow.
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document.write( "Make this chart:\r\n" );
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document.write( "           distance     rate     time\r\n" );
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document.write( "snowplow      \r\n" );
document.write( "car         \r\n" );
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document.write( "Let x = the snowplow's rate.\r\n" );
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document.write( "The car begins at 8AM and reaches the snowplow at 8:20AM.\r\n" );
document.write( "So the car's travel time is 20 minutes or 20/60 or 1/3 hour.\r\n" );
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document.write( "The snowplow begins at 6AM and plows till 8:20AM when the car catches up.\r\n" );
document.write( "So the snowplow's time is 2 hours 20 minutes or 2 1/3 hours, or 7/3 hours.\r\n" );
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document.write( "The car's rate is 35 mph, \r\n" );
document.write( "So fill those four in: \r\n" );
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document.write( "           distance     rate     time\r\n" );
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document.write( "snowplow                  x       7/3   \r\n" );
document.write( "car                      35       1/3 \r\n" );
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document.write( "Now fill in the distances using distance=(rate)(time)\r\n" );
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document.write( "The snowplow's distance = (rate)(time) = x(7/3) = (7/3)x \r\n" );
document.write( "The car's distance = (rate)(time) = 35(1/3) = 35/3\r\n" );
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document.write( "Fill those in\r\n" );
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document.write( "           distance     rate     time\r\n" );
document.write( "----------------------------------------\r\n" );
document.write( "snowplow    (7/3)x        x       7/3   \r\n" );
document.write( "car          35/3        35       1/3\r\n" );
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document.write( "They go the same distance, so we set the two \r\n" );
document.write( "distances equal to each other:\r\n" );
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document.write( "      (7/3)x = 35/3\r\n" );
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document.write( "Multiply both sides by 3\r\n" );
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document.write( "          7x = 35\r\n" );
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document.write( "Divide both sides by 7\r\n" );
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document.write( "           x = 5 \r\n" );
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document.write( "The snowplow is going 5 mph.\r\n" );
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document.write( "Edwin

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