document.write( "Question 697168: A chemist wants to make 700mL of a 6% acid solution by using 5% and 12% acid solutions. How much of each should she use?
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Algebra.Com's Answer #429720 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = ml of 5% solution needed
\n" ); document.write( "Let $\"+b+\"$ = ml of 12% solution needed
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+a+%2B+b+=+700+\"$
\n" ); document.write( "(2) $\"+%28+.05a+%2B+.12b+%29+%2F+700+=+.06+\"$
\n" ); document.write( "------------------------------
\n" ); document.write( "(2) $\"+.05a+%2B+.12b+=+.06%2A700+\"$
\n" ); document.write( "(2) $\"+.05a+%2B+.12b+=+42+\"$
\n" ); document.write( "(2) $\"+5a+%2B+12b+=+4200+\"$
\n" ); document.write( "Multiply both sides of (1) by $\"+5+\"$
\n" ); document.write( "and subtract (1) from (2)
\n" ); document.write( "(2) $\"+5a+%2B+12b+=+4200+\"$
\n" ); document.write( "(1) $\"+-5a+-+5b+=+-3500+\"$
\n" ); document.write( " $\"+7b+=+700+\"$
\n" ); document.write( " $\"+b+=+100+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+a+%2B+b+=+700+\"$
\n" ); document.write( "(1) $\"+a+%2B+100+=+700+\"$
\n" ); document.write( "(1) $\"+a+=+600+\"$
\n" ); document.write( "600 ml of 5% solution is needed
\n" ); document.write( "100 ml of 12% solution is needed
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\n" ); document.write( "check answer:
\n" ); document.write( "(2) $\"+%28+.05%2A600+%2B+.12%2A100+%29+%2F+700+=+.06+\"$
\n" ); document.write( "(2) $\"+%28+30+%2B+12+%29+%2F+700+=+.06+\"$
\n" ); document.write( "(2) $\"+42+=+.06%2A700+\"$
\n" ); document.write( "(2) $\"+42+=+42+\"$
\n" ); document.write( "OK
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