document.write( "Question 854340: It takes Ralph 14 hours to paint a fence alone. Lisa can do the same job in 16 hours. If Ralph paints alone for 25 minutes before Lisa begins helping, how long must they work together to finish painting the fence? Give your answer as a simplified fraction. \n" ); document.write( "
Algebra.Com's Answer #514619 by josmiceli(19441)\"\" \"About 
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Ralph's rate of painting is:
\n" ); document.write( "( 1 fence ) / ( 14 hrs )
\n" ); document.write( "He paints the fence alone for \"+25%2F60+=+5%2F12+\" hr
\n" ); document.write( "I can say:
\n" ); document.write( "( fraction of the fence he paints ) = ( his rate of painting ) x ( time spent painting )
\n" ); document.write( "fraction of the fence he paints = \"+%28+1%2F14+%29%2A%28+5%2F12+%29+=+5%2F168+\"
\n" ); document.write( "That means there is \"+1+-+5%2F168+=+163%2F168+\"
\n" ); document.write( "of the fence left to paint
\n" ); document.write( "------------------------
\n" ); document.write( "Let \"+t+\" = the time in hours for them to paint \"+163%2F168+\"
\n" ); document.write( "of the fence painting together
\n" ); document.write( "Add their rates of painting to find rate painting together
\n" ); document.write( "\"+1%2F14+%2B+1%2F16+=+%28+163%2F168+%29+%2F+t+\"
\n" ); document.write( "Multiply both sides by \"+168%2A2%2At+=+336t+\"
\n" ); document.write( "\"+24t+%2B+21t+=+326+\"
\n" ); document.write( "\"+45t+=+326+\"
\n" ); document.write( "\"+t+=+7.2444+\" hrs
\n" ); document.write( "and
\n" ); document.write( "\"+.2444%2A60+=+14.667+\" min
\n" ); document.write( "--------------------------
\n" ); document.write( "Working together, they finish the fence in 7 hrs 14 min 40 sec
\n" ); document.write( "As a simplified fraction, expressed in hours, this is:
\n" ); document.write( "\"+326%2F45+\" hrs
\n" ); document.write( "--------------------------
\n" ); document.write( "check answer using calculator:
\n" ); document.write( "\"+1%2F14+%2B+1%2F16+=+%28+163%2F168+%29+%2F+t+\"
\n" ); document.write( "\"+1%2F14+%2B+1%2F16+=+%28+163%2F168+%29+%2F+%28+326%2F45+%29+\"
\n" ); document.write( "\"+.071429+%2B+.0625+=+.97024+%2F+7.2444+\"
\n" ); document.write( "\"+.133929+=+.133929+\"
\n" ); document.write( "OK\r
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