document.write( "Question 168173: It takes Lucy 15 minutes longer to clean her garage alone than it takes her brother Billy. Together they can clean the garage in 4 minutes. If Lucy were cleaning the garage alone, how long would it take her to complete the job? \n" ); document.write( "
Algebra.Com's Answer #123931 by ankor@dixie-net.com(22740)\"\" \"About 
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:
\n" ); document.write( "It takes Lucy 15 minutes longer to clean her garage alone than it takes her brother Billy.
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\n" ); document.write( "Together they can clean the garage in 4 minutes.
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\n" ); document.write( "If Lucy were cleaning the garage alone, how long would it take her to complete the job?
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\n" ); document.write( "Let x = L's time (in minutes) working alone
\n" ); document.write( "then
\n" ); document.write( "(x-15) = B's time working alone
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\n" ); document.write( "Let the completed job = 1
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\n" ); document.write( "\"4%2F%28%28x-15%29%29\" + \"4%2Fx\" = 1
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\n" ); document.write( "Multiply equation by x(x-15) to get rid of the denominators, results:
\n" ); document.write( "4x + 4(x-15) = x(x-15)
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\n" ); document.write( "4x + 4x - 60 = x^2 - 15x
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\n" ); document.write( "8x - 60 = x^2 - 15x
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\n" ); document.write( "Arrange as a quadratic equation:
\n" ); document.write( "x^2 - 15x - 8x + 60 = 0
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\n" ); document.write( "x^2 - 23x + 60 = 0
\n" ); document.write( "Factor this to:
\n" ); document.write( "(x - 3)(x - 20)
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\n" ); document.write( "x = 3 does not make sense
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\n" ); document.write( "x = 20 min, L's time working alone.
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\n" ); document.write( "Check solution; B's time would be 20 - 15 = 5 min
\n" ); document.write( "\"4%2F5\" + \"4%2F20\" = 1
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