document.write( "Question 742877: a pharmacist has 10% and 30% alcohol solutions instock. to prepare 200mL of 25% solution how much should a pharmacist mix? \n" ); document.write( "

Algebra.Com's Answer #452655 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = mL of 10% solution needed
\n" ); document.write( "Let $\"+b+\"$ = mL of 30% solution needed
\n" ); document.write( " $\"+.1a+\"$ = mL of alcohol in 10% solution
\n" ); document.write( " $\"+.3a+\"$ = mL of alcohol in 30% solution
\n" ); document.write( "-----------------
\n" ); document.write( "(1) $\"+%28+.1a+%2B+.3b+%29+%2F+200+=+.25+\"$ mL
\n" ); document.write( "(2) $\"+a+%2B+b+=+200+\"$ mL
\n" ); document.write( "---------------------
\n" ); document.write( "(1) $\"+.1a+%2B+.3b+=+50+\"$
\n" ); document.write( "(1) $\"+a+%2B+3b+=+500+\"$
\n" ); document.write( "-------------------
\n" ); document.write( "Subtract (2) from (1)
\n" ); document.write( "(1) $\"+a+%2B+3b+=+500+\"$
\n" ); document.write( "(2) $\"+-a+-+b+=+-200+\"$
\n" ); document.write( " $\"+2b+=+300+\"$
\n" ); document.write( " $\"+b+=+150+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(2) $\"+a+%2B+150+=+200+\"$
\n" ); document.write( "(2) $\"+a+=+50+\"$
\n" ); document.write( "-------------
\n" ); document.write( "50 mL of 10% solution is needed
\n" ); document.write( "150 mL of 30% solution is needed
\n" ); document.write( "check:
\n" ); document.write( "(1) $\"+%28+.1%2A50+%2B+.3%2A150+%29+%2F+200+=+.25+\"$
\n" ); document.write( "(1) $\"+%28+5+%2B+45+%29+%2F+200+=+.25+\"$
\n" ); document.write( "(1) $\"+50+=+.25%2A200+\"$
\n" ); document.write( "(1) $\"+50+=+50+\"$
\n" ); document.write( "OK\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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