document.write( "Question 1021361: Jonathan can paint a room in 8 hrs. After painting for 2 hours, his brother, David joined him and together, they finished painting the room in 3 1/3hours. In how many hours will David finish painting the room alone? \n" ); document.write( "

Algebra.Com's Answer #637212 by fractalier(6550) $\"\"$ $\"About$

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The normal set up is
\n" ); document.write( " $\"t%2FA+%2B+t%2FB+=+1\"$
\n" ); document.write( "In our case A = 8, the 1 job is now only 3/4 of a job (since Jon did 1/4 of it already), and the time worked together, t, is 10/3 hours...so we have
\n" ); document.write( " $\"%2810%2F3%29%2F8+%2B+%2810%2F3%29%2FB+=+3%2F4\"$
\n" ); document.write( "We need B. Multiply everything by 8B and get
\n" ); document.write( " $\"%2810%2F3%29B+%2B+80%2F3+=+6B\"$
\n" ); document.write( "Now multiply by 3 to clear fractions and get
\n" ); document.write( " $\"10B+%2B+80+=+18B\"$
\n" ); document.write( " $\"8B+=+80\"$ and
\n" ); document.write( "B = 10 hours \n" ); document.write( "

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