document.write( "Question 606141: A pharmacist mixed some 10%-saline solution with some 15%-saline solution to obtain 100 mL of a 12%-saline solution. How much of the 10%-saline solution did the pharmacist use in the mixture?
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Algebra.Com's Answer #381932 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"+a+\"$ = ml of 10% solution needed
\n" ); document.write( "Let $\"+b+\"$ = ml of 15% solution needed
\n" ); document.write( " $\"+.1a+\"$ = ml of salt in 10% solution
\n" ); document.write( " $\"+.15b+\"$ = ml of salt in 15% solution
\n" ); document.write( "----------------
\n" ); document.write( "(1) $\"+%28+.1a+%2B+.15b+%29+%2F+100+=+.12+\"$
\n" ); document.write( "(2) $\"+a+%2B+b+=+100+\"$
\n" ); document.write( "----------------
\n" ); document.write( "(1) $\"+.1a+%2B+.15b+=+12+\"$
\n" ); document.write( "(1) $\"+10a+%2B+15b+=+1200+\"$
\n" ); document.write( "Multiply both sides of (2) by $\"+10+\"$
\n" ); document.write( "and subtract (2) from (1)
\n" ); document.write( "(1) $\"+10a+%2B+15b+=+1200+\"$
\n" ); document.write( "(2) $\"+-10a+-+10b+=+-1000+\"$
\n" ); document.write( " $\"+5b+=+200+\"$
\n" ); document.write( " $\"+b+=+40+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(2) $\"+a+%2B+b+=+100+\"$
\n" ); document.write( "(2) $\"+a+%2B+40+=+100+\"$
\n" ); document.write( "(2) $\"+a+=+100+-+40+\"$
\n" ); document.write( "(2) $\"+a+=+60+\"$
\n" ); document.write( "60 ml of 10% solution is needed
\n" ); document.write( "check answer
\n" ); document.write( "(1) $\"+%28+.1a+%2B+.15b+%29+%2F+100+=+.12+\"$
\n" ); document.write( "(1) $\"+%28+.1%2A60+%2B+.15%2A40+%29+%2F+100+=+.12+\"$
\n" ); document.write( "(1) $\"++6+%2B+6+=+.12%2A100+\"$
\n" ); document.write( "(1) $\"+12+=+12+\"$
\n" ); document.write( "OK\r
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