document.write( "Question 158343: A 40% antifreeze solution and a 70% antifreeze solution is mixed to make 12 gallons of 50% antifrezze solution. How many gallons of each antifreeze solution should be used. \n" ); document.write( "

Algebra.Com's Answer #116709 by jojo14344(1513) $\"\"$ $\"About$

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Let:
\n" ); document.write( "40% a/f = $\"x\"$
\n" ); document.write( "70% a/f = $\"y\"$
\n" ); document.write( "Number of gallons of $\"x\"$ + $\"y\"$ equals $\"12gal\"$
\n" ); document.write( " $\"x%2By=12\"$ ------------------> eqn 1
\n" ); document.write( "We get, $\"y=12-x\"$ ----------> eqn 2
\n" ); document.write( "Also,
\n" ); document.write( " $\"0.40x%2B0.70y=0.50%2812%29\"$ ----> eqn 3
\n" ); document.write( "Substitute eqn 2 in eqn 3:
\n" ); document.write( " $\"0.40x%2B0.70%2812-x%29=6\"$
\n" ); document.write( " $\"0.40x%2B8.4-0.70x=6\"$
\n" ); document.write( " $\"8.4-6=0.70x-0.40x\"$
\n" ); document.write( " $\"2.4=0.30x\"$ ----> $\"cross%282.4%298%2Fcross%280.30%29=cross%280.30%29x%2Fcross%280.30%29\"$
\n" ); document.write( " $\"x=8gal\"$ ----------------------> for the 40% a/f
\n" ); document.write( "In eqn 2:
\n" ); document.write( " $\"y=12-8=4gal\"$ ----------------> for the 70% a/f
\n" ); document.write( "In doubt? go back eqn 3:
\n" ); document.write( " $\"0.40%288%29%2B0.70%284%29=0.50%2812%29\"$
\n" ); document.write( " $\"3.2%2B2.8=6\"$
\n" ); document.write( " $\"6=6\"$
\n" ); document.write( "Thank you,
\n" ); document.write( "Jojo
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