document.write( "Question 313379: Linda drove to her boyfriend's house and found him waxing his car. This job usually takes him 3 hours. She wanted her boyfriend to take her to the show which was starting in 2 hours. She offered to help him, but she knew she would need 4 hours to wax the car by herself. She wondered how long both of them would need to wax the car. Calculate the number of hours it will take. (Round your answer to the nearest tenth.) \n" ); document.write( "

Algebra.Com's Answer #224065 by Edwin McCravy(20055) $\"\"$ $\"About$

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Linda drove to her boyfriend's house and found him waxing his car. This job usually takes him 3 hours. She wanted her boyfriend to take her to the show which was starting in 2 hours. She offered to help him, but she knew she would need 4 hours to wax the car by herself. She wondered how long both of them would need to wax the car. Calculate the number of hours it will take. (Round your answer to the nearest tenth.)
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document.write( "Make this chart\r\n" );
document.write( "                       Number of      Time      Rate in\r\n" );
document.write( "                       Cars waxed   Required    cars/hr.\r\n" );
document.write( "Linda alone         |             |          | \r\n" );
document.write( "---------------------------------------------------------\r\n" );
document.write( "bf alone            |             |          |\r\n" );
document.write( "----------------------------------------------------------\r\n" );
document.write( "Linda & bf together |             |          |\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "We want to to know the time for both Linda and her bf working\r\n" );
document.write( "together to wax the car.   So we let x represent this time\r\n" );
document.write( "and put x for the time required for them working together to\r\n" );
document.write( "wax 1 car.  So fill in x for their time working together and\r\n" );
document.write( "1 for the number of cars they can wax in x hours working\r\n" );
document.write( "together.\r\n" );
document.write( "\r\n" );
document.write( "                       Number of      Time      Rate in\r\n" );
document.write( "                       Cars waxed   Required    cars/hr.\r\n" );
document.write( "Linda alone         |             |          | \r\n" );
document.write( "--------------------|-------------|----------|-----------\r\n" );
document.write( "bf alone            |             |          |\r\n" );
document.write( "--------------------|-------------|----------|------------\r\n" );
document.write( "Linda & bf together |      1      |     x    |\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "Linda's bf can wax 1 car in 3 hours, so we place 1 for the\r\n" );
document.write( "number of cars and 3 for his number of hours:\r\n" );
document.write( "\r\n" );
document.write( "                       Number of      Time      Rate in\r\n" );
document.write( "                       Cars waxed   Required    cars/hr.\r\n" );
document.write( "Linda alone         |             |          | \r\n" );
document.write( "--------------------|-------------|----------|-----------\r\n" );
document.write( "bf alone            |      1      |     3    |\r\n" );
document.write( "--------------------|-------------|----------|------------\r\n" );
document.write( "Linda & bf together |      1      |     x    |\r\n" );
document.write( " \r\n" );
document.write( "\r\n" );
document.write( "Linda can wax 1 car in 4 hours, so we place 1 for the\r\n" );
document.write( "number of cars and 4 for her number of hours:\r\n" );
document.write( "\r\n" );
document.write( "                       Number of      Time      Rate in\r\n" );
document.write( "                       Cars waxed   Required    cars/hr.\r\n" );
document.write( "Linda alone         |      1      |     4    | \r\n" );
document.write( "--------------------|-------------|----------|-----------\r\n" );
document.write( "bf alone            |      1      |     3    |\r\n" );
document.write( "--------------------|-------------|----------|------------\r\n" );
document.write( "Linda & bf together |      1      |     x    |\r\n" );
document.write( "\r\n" );
document.write( "Now we fill in the rates in cars/hr. by dividing the number of \r\n" );
document.write( "cars by the number of hours.\r\n" );
document.write( "\r\n" );
document.write( "                       Number of      Time      Rate in\r\n" );
document.write( "                       Cars waxed   Required    cars/hr.\r\n" );
document.write( "Linda alone         |      1      |     4    |    1/4 \r\n" );
document.write( "--------------------|-------------|----------|-----------\r\n" );
document.write( "bf alone            |      1      |     3    |    1/3\r\n" );
document.write( "--------------------|-------------|----------|------------\r\n" );
document.write( "Linda & bf together |      1      |     x    |    1/x\r\n" );
document.write( "\r\n" );
document.write( "We for the equation from this:\r\n" );
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document.write( "    Linda's rate + bf's rate = their rate together:\r\n" );
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document.write( "          1/4    +    1/3    =     1/x\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( "You get hrs or hrs, about 1 hour and 43 minutes.\r\n" );
document.write( "So it it doesn't take more than 17 minutes to drive and get seated at\r\n" );
document.write( "the show, they can still make it.  But of course they could just go in\r\n" );
document.write( "her car and finish waxing his car after the show. :-)\r\n" );
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document.write( "Edwin

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