document.write( "Question 974965: It takes Sam 10 hours to build a section of fence. When David helps him, they can build a section together in 3 hours. How long would it take David to build a section alone? \n" ); document.write( "
Algebra.Com's Answer #596793 by josgarithmetic(39625)\"\" \"About 
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Their combined rate is the sum of their individual rates. SECTION per HOUR is the unit for rate. \n" ); document.write( "
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