document.write( "Question 58158: A metallurgist has one alloy containing 20% copper and another containing 70% copper. How many pounds of alloy must he use to make 50 pounds of the a third alloy containing 50% copper?\r
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Algebra.Com's Answer #39943 by Nate(3500)\"\" \"About 
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x = amount of 20% copper
\n" ); document.write( "y = amount of 70% copper
\n" ); document.write( "*Remember: x = 50 - y
\n" ); document.write( "(0.2x + 0.7y)/50 = 0.5
\n" ); document.write( "0.2x + 0.7y = 25
\n" ); document.write( "0.2(50 - y) + 0.7y = 25
\n" ); document.write( "10 - 0.2y + 0.7y = 25
\n" ); document.write( "0.5y = 15
\n" ); document.write( "y = 30
\n" ); document.write( "x = 50 - y = 50 - 30 = 20
\n" ); document.write( "30 pounds of 70% copper
\n" ); document.write( "20 pounds of 20% copper
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