document.write( "Question 407455: If it takes workers A and B 2 days to complete a job. And it takes workers B and C 3 days to complete the same job. And it takes workers A and C 4 days to complete this job how long does it take each worker to do this job alone. And what formulas are used. \n" ); document.write( "
Algebra.Com's Answer #287375 by ankor@dixie-net.com(22740)\"\" \"About 
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If it takes workers A and B 2 days to complete a job.
\n" ); document.write( " And it takes workers B and C 3 days to complete the same job.
\n" ); document.write( " And it takes workers A and C 4 days to complete this job how long does it take
\n" ); document.write( " each worker to do this job alone.
\n" ); document.write( ":
\n" ); document.write( "Let a, b, c, represent the time required by each work alone
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\n" ); document.write( "Let the completed job = 1
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\n" ); document.write( "Write a shared work equation for each statement:
\n" ); document.write( ":
\n" ); document.write( "\"If it takes workers A and B 2 days to complete a job.\"
\n" ); document.write( "\"2%2Fa\" + \"2%2Fb\" = 1
\n" ); document.write( ":
\n" ); document.write( "\"If it takes workers B and C 3 days to complete the same job.\"
\n" ); document.write( "\"3%2Fb\" + \"3%2Fc\" = 1
\n" ); document.write( ":
\n" ); document.write( "\"it takes workers A and C 4 days to complete this job\"
\n" ); document.write( "\"4%2Fa\" + \"4%2Fc\" = 1
\n" ); document.write( ":
\n" ); document.write( "Add all three equations to give us another equation to work with
\n" ); document.write( "\"2%2Fa\" + \"2%2Fb\" + \"0%2Fc\" = 1
\n" ); document.write( "\"0%2Fa\" + \"3%2Fb\" + \"3%2Fc\" = 1
\n" ); document.write( "\"4%2Fa\" + \"0%2Fb\" + \"4%2Fc\" = 1
\n" ); document.write( "---------------------------------------
\n" ); document.write( "\"6%2Fa\" + \"5%2Fb\" + \"7%2Fc\" = 3
\n" ); document.write( ":
\n" ); document.write( "Multiply the 1st equation by 3, subtract the above equation from it
\n" ); document.write( "\"6%2Fa\" + \"6%2Fb\" + \"0%2Fc\" = 3
\n" ); document.write( "\"6%2Fa\" + \"5%2Fb\" + \"7%2Fc\" = 3
\n" ); document.write( "---------------------------------------subtraction eliminates a
\n" ); document.write( "\"0%2Fa\" + \"1%2Fb\" - \"7%2Fc\" = 0
\n" ); document.write( ":
\n" ); document.write( "\"1%2Fb\" = \"7%2Fc\"
\n" ); document.write( "Cross multiply
\n" ); document.write( "c = 7b
\n" ); document.write( ":
\n" ); document.write( "In equation: \"3%2Fb\" + \"3%2Fc\" = 1, replace c with 7b
\n" ); document.write( "\"3%2Fb\" + \"3%2F7b\" = 1
\n" ); document.write( "Multiply by 7b, results
\n" ); document.write( "7(3) + 3 = 7b
\n" ); document.write( "21 + 3 = 7b
\n" ); document.write( "24 = 7b
\n" ); document.write( "b = \"24%2F7\"
\n" ); document.write( "b = 3.43 hrs, B alone
\n" ); document.write( ":
\n" ); document.write( "Find c
\n" ); document.write( "c = 7b
\n" ); document.write( "c = 7(3.43)
\n" ); document.write( "c = 24 hrs, C alone
\n" ); document.write( ":
\n" ); document.write( "Find a using, \"4%2Fa\" + \"4%2Fc\" = 1; replace c with 24
\n" ); document.write( "\"4%2Fa\" + \"4%2F24\" = 1
\n" ); document.write( "multiply by 24a
\n" ); document.write( "24(4) + 4a = 24a
\n" ); document.write( "96 = 24a - 4a
\n" ); document.write( "96 = 20a
\n" ); document.write( "a = \"96%2F20\"
\n" ); document.write( "a = 4.8 hrs, A alone
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check this in the 1st equation
\n" ); document.write( "\"2%2F4.8\" + \"2%2F3.43\" = 1
\n" ); document.write( ".42 + .58 = 1 confirms our solutions of:
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\n" ); document.write( "A = 4.8 hrs, B = 3.43 hrs, C = 24 hrs (almost useless) \r
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