document.write( "Question 1184804: X and Y can assemble machine parts together in 30 days. They started work and Y left work after 20 days. X assemnled the remaining machine parts in 20 days. In how many days X can assemble machine parts by himself? \n" ); document.write( "
Algebra.Com's Answer #815440 by josgarithmetic(39627)\"\" \"About 
You can put this solution on YOUR website!
\"1%2Fx%2B1%2Fy=1%2F30\"\r
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\n" ); document.write( "\n" ); document.write( "\"20%281%2Fx%2B1%2Fy%29%2B20%281%2Fx%29=1\"\r
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\n" ); document.write( "\n" ); document.write( "\"system%281%2Fx%2B1%2Fy=1%2F30%2C2%2Fx%2B1%2Fy=1%2F20%29\"\r
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\n" ); document.write( "\n" ); document.write( "Equations might be easier to handle if a substitution is made:
\n" ); document.write( "\"u=1%2Fx\" and \"v=1%2Fy\"\r
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\n" ); document.write( "\n" ); document.write( "\"system%28u%2Bv=1%2F30%2C2u%2Bv=1%2F20%29\"
\n" ); document.write( "Elimination Method should be easier this way.\r
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\n" ); document.write( "\n" ); document.write( "E2-E1:
\n" ); document.write( "\"u=1%2F20-1%2F30\"\r
\n" ); document.write( "\n" ); document.write( "\"u=3%2F60-2%2F60\"\r
\n" ); document.write( "\n" ); document.write( "\"u=1%2F60\"\r
\n" ); document.write( "\n" ); document.write( "Back-substituting, \"1%2Fx=1%2F60\"------------\"highlight%28x=60%29\"
\n" ); document.write( "and you can solve for y whatever way you want.
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