document.write( "Question 536485: Charles is doing an experiment that calls for a 40% solution of copper sulfate. He has 60 mL of a 25% solution. How many milliliters of a 70% solution should Charles add to obtain the required 40% solution? \n" ); document.write( "

Algebra.Com's Answer #352390 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+x+\"$ = ml of 70% solution needed
\n" ); document.write( "given:
\n" ); document.write( " $\"+.7x+\"$ = ml of copper sulfate in 70% solution
\n" ); document.write( " $\"+.25%2A60+=+15+\"$ ml of copper sulfate in 25% solution
\n" ); document.write( "----------------
\n" ); document.write( "In words:
\n" ); document.write( "( final ml of copper sulfate ) / ( final ml of solution ) = 40%
\n" ); document.write( " $\"+%28+.7x+%2B+15+%29+%2F+%28+x+%2B+60+%29+=+.4+\"$
\n" ); document.write( " $\"+.7x+%2B+15+=+.4%2A%28+x+%2B+60+%29+\"$
\n" ); document.write( " $\"+.7x+%2B+15+=+.4x+%2B+24+\"$
\n" ); document.write( " $\"+.3x+=+24+-+15+\"$
\n" ); document.write( " $\"+.3x+=+9+\"$
\n" ); document.write( " $\"+x+=+30+\"$
\n" ); document.write( "30 ml of 70% solution are needed
\n" ); document.write( "check:
\n" ); document.write( " $\"+%28+.7%2A30+%2B+15+%29+%2F+%28+30+%2B+60+%29+=+.4+\"$
\n" ); document.write( " $\"+%28+21+%2B+15+%29+%2F+90+=+.4+\"$
\n" ); document.write( " $\"+36+=+.4%2A90+\"$
\n" ); document.write( " $\"+36+=+36+\"$
\n" ); document.write( "OK \n" ); document.write( "

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