document.write( "Question 911345: How much pure copper must be added to 50 kg of an alloy containing 12% copper to raise the copper content to 21%? \n" ); document.write( "

Algebra.Com's Answer #553038 by lwsshak3(11628) $\"\"$ $\"About$

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How much pure copper must be added to 50 kg of an alloy containing 12% copper to raise the copper content to 21%?
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\n" ); document.write( "let x=amt of pure copper to add:
\n" ); document.write( "12%*50+100%x=21%(50+x)
\n" ); document.write( "6+x=10.5+.21x
\n" ); document.write( ".79x=4.5
\n" ); document.write( "x=5.7
\n" ); document.write( "amt of pure copper to add: 5.7 kg \n" ); document.write( "

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