document.write( "Question 534086: A silversmith has two alloys, one containing 70% silver and the other 20% silver. How much of each should be melted and combined to obtain 500 grams of an alloy containing 55% silver? \n" ); document.write( "
Algebra.Com's Answer #351311 by KMST(5328)\"\" \"About 
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Let x be the amount (in grams) of the 70% alloy.
\n" ); document.write( "Let y be the amount (in grams) of the 20% alloy.
\n" ); document.write( "We want
\n" ); document.write( "\"x%2By=500\" and
\n" ); document.write( "\"0.7x%2B0.2y=0.55%2A500\" or \"0.7x%2B0.2y=275\"
\n" ); document.write( "Now we have a system of linear equations:
\n" ); document.write( "\"x%2By=500\" and
\n" ); document.write( "\"0.7x%2B0.2y=275\"
\n" ); document.write( "We can solve by elimination like this:
\n" ); document.write( "multiply the first equation times -0.2 to get
\n" ); document.write( "\"-0.2x-0.2y=-100\"
\n" ); document.write( "and add it to the second equation to eliminate y, getting
\n" ); document.write( "\"0.5x=175\" so \"x=175%2F0.5=340\"
\n" ); document.write( "Plugging that value back into
\n" ); document.write( "\"x%2By=500\" we get
\n" ); document.write( "\"340%2By=500\" so \"y=500-340=150\"
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