document.write( "Question 704562: A butcher has some hamburger that is 21% fat and some that is 15% fat. How many pounds of each should be mixed to make 75 lb of hamburger that is 17% fat? \n" ); document.write( "

Algebra.Com's Answer #434161 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = pounds of 21% hamburger needed
\n" ); document.write( "Let $\"+b+\"$ = pound of 15% hamburger needed
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+a+%2B+b+=+75+\"$
\n" ); document.write( "(2) $\"+%28+.21a+%2B+.15b+%29+%2F+75+=+.17+\"$
\n" ); document.write( "-----------------------------
\n" ); document.write( "(2) $\"+.21a+%2B+.15b+=+.17%2A75+\"$
\n" ); document.write( "(2) $\"+.21a+%2B+.15b+=+12.75+\"$
\n" ); document.write( "(2) $\"+21a+%2B+15b+=+1275+\"$
\n" ); document.write( "Multiply both sides of (1) by $\"+15+\"$ and
\n" ); document.write( "subtract (1) from (2)
\n" ); document.write( "(2) $\"+21a+%2B+15b+=+1275+\"$
\n" ); document.write( "(1 ) $\"+-15a+-+15b+=+-1125+\"$
\n" ); document.write( " $\"+6a+=+150+\"$
\n" ); document.write( " $\"+a+=+25+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+25+%2B+b+=+75+\"$
\n" ); document.write( "(1) $\"+b+=+50+\"$
\n" ); document.write( "25 pounds of 21% hamburger are needed
\n" ); document.write( "50 pound of 15% hamburger are needed
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+%28+.21%2A25+%2B+.15%2A50+%29+%2F+75+=+.17+\"$
\n" ); document.write( "(2) $\"+%28+5.25+%2B+7.5+%29+%2F+75+=+.17+\"$
\n" ); document.write( "(2) $\"+12.75+%2F+75+=+.17+\"$
\n" ); document.write( "(2) $\"+12.75+=+.17%2A75+\"$
\n" ); document.write( "(2) $\"+12.75+=+12.75+\"$
\n" ); document.write( "OK\r
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