document.write( "Question 821700: It takes John and Amy Brogan 6 hours to build a sandcastle. It takes Paul and Cindy Carter 4 hours to make the same sandcastle. How long will it take all four people together to build the sandcastle? \n" ); document.write( "

Algebra.Com's Answer #494968 by richwmiller(17219) $\"\"$ $\"About$

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1/a+1/j=1/6,
\n" ); document.write( "1/p+1/c=1/4,
\n" ); document.write( "1/a+1/j+1/p+1/c=1/x,
\n" ); document.write( "1/6+1/4=1/x
\n" ); document.write( "4/24+6/24=1/x
\n" ); document.write( "10/24=1/x
\n" ); document.write( "x=2.4 hours for all four together\r
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