document.write( "Question 850678: A can do a certain work in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in.... \n" ); document.write( "
Algebra.Com's Answer #512301 by josgarithmetic(39617)\"\" \"About 
You can put this solution on YOUR website!
Use all rates as Jobs per Days. Notice that C worker is given enough direct information for a rate value. Start with the rate for C, and create rate equations for B & C, and for A & B.\r
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\n" ); document.write( "\n" ); document.write( "Rate for C: \"1%2F50\" jobs per day.\r
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\n" ); document.write( "\n" ); document.write( "Let x = time for A to do 1 job.
\n" ); document.write( "Let y = time for B to do 1 job.\r
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\n" ); document.write( "\n" ); document.write( "First sentence tells, rate for A is equal to the combined rate of B and C.
\n" ); document.write( "\"1%2Fx=1%2Fy%2B1%2F50\"
\n" ); document.write( "LCD is 50xy.
\n" ); document.write( "\"50%2Axy%2Fx=50%2Axy%2Fy%2B50%2Axy%2F50\"
\n" ); document.write( "\"50y=50x%2Bxy\"\r
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\n" ); document.write( "\n" ); document.write( "Second sentence tells, A and B together do the job in 10 days:
\n" ); document.write( "\"%281%2Fx%2B1%2Fy%29=1%2F10\"
\n" ); document.write( "LCD is 10xy.
\n" ); document.write( "\"10xy%2Fx%2B10xy%2Fy=10xy%2F10\"
\n" ); document.write( "\"10y%2B10x=xy\"\r
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\n" ); document.write( "\n" ); document.write( "The system to solve for x and y is:
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\n" ); document.write( "\"50y=50x%2Bxy\"
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\n" ); document.write( "\"10y%2B10x=xy\"
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\n" ); document.write( "\n" ); document.write( "Solving each of those for xy, and then equating each expression's formula for xy gives \"50y-50x=10y%2B10x\"
\n" ); document.write( "simplifying to
\n" ); document.write( "\"2y=3x\"
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\n" ); document.write( "Solving the linear equation for a variable, trying y, \"y=3x%2F3\";
\n" ); document.write( "Picking either system equation, trying \"10y%2B10x=xy\", and substitute the expression for y found,
\n" ); document.write( "\"highlight_green%2810%283x%2F2%29%2B10x=x%283x%2F2%29%29\"
\n" ); document.write( "Multiply left and right members by 2, and be sure to obtain this equation:
\n" ); document.write( "\"3x%5E2-50=0\" -----do not try to divide either sides by x thinking that to be simplification; it's a common beginners mistake.
\n" ); document.write( "\"highlight_green%28x%283x-50%29=0%29\"
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\n" ); document.write( "The meaningful answer for x is that \"highlight%28x=50%2F3=16%262%2F3%29\"
\n" ); document.write( ".. and use either system equation to find or solve for y. You can also use the linear \"highlight%28y=%283%2F2%29x%29\" found earlier.
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