document.write( "Question 911995: Fred can repair the roof in 4 hours. If Sandy helps, it takes them 3 hours. Without help, how long would it take for Sandy to repair the roof? \n" ); document.write( "
Algebra.Com's Answer #553492 by richwmiller(17219)\"\" \"About 
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rate for A alone 4
\n" ); document.write( "rate for A & B together 3
\n" ); document.write( "1/a+1/b=1/x
\n" ); document.write( "1/4+1/b=1/3
\n" ); document.write( "1/b=1/3-1/4
\n" ); document.write( "1/b=4/12-3/12
\n" ); document.write( "1/b=1/12
\n" ); document.write( "1/b=1/12
\n" ); document.write( "b=12
\n" ); document.write( "rate for B alone 12
\n" ); document.write( "check
\n" ); document.write( "1/4+1/12=1/3
\n" ); document.write( "12/48+4/48=1/3
\n" ); document.write( "16/48=1/3
\n" ); document.write( "ok
\n" ); document.write( "codewa
\n" ); document.write( " \n" ); document.write( "
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