document.write( "Question 324939: A contractor mixes concrete from bags of pre-mix for small jobs. How many bags with 7% cement should he mix with 10 bags of 15.5% cement to produce a mix containing 12% cement? \n" ); document.write( "
Algebra.Com's Answer #232700 by Fombitz(32388)\"\" \"About 
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Let the number of 7% bags be Y.
\n" ); document.write( "\"7Y%2B15.5%2810%29=12%28Y%2B10%29\"
\n" ); document.write( "\"7Y%2B155=12Y%2B120\"
\n" ); document.write( "\"-5Y=-35\"
\n" ); document.write( "\"Y=7\"
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\n" ); document.write( "7 bags of 7% cement need to be added.
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