document.write( "Question 752579: How much pure acid should be mixed with 5 gallons of a 40% acid solution in order to get a 90% acid solution? \n" ); document.write( "

Algebra.Com's Answer #457872 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+x+\"$ = gallons of pure acid to be added
\n" ); document.write( " $\"+.4%2A5+=+2+\"$ gallons of acid in 40% solution
\n" ); document.write( "---------------
\n" ); document.write( " $\"+%28+2+%2B+x+%29+%2F+%28+5+%2B+x+%29+=+.9+\"$
\n" ); document.write( " $\"+2+%2B+x+=+.9%2A%28+5+%2B+x+%29+\"$
\n" ); document.write( " $\"+2+%2B+x+=+4.5+%2B+.9x+\"$
\n" ); document.write( " $\"+.1x+=+2.5+\"$
\n" ); document.write( " $\"+x+=+25+\"$
\n" ); document.write( "25 gallons of pure acid must be added
\n" ); document.write( "check:
\n" ); document.write( " $\"+%28+2+%2B+x+%29+%2F+%28+5+%2B+x+%29+=+.9+\"$
\n" ); document.write( " $\"+%28+2+%2B+25+%29+%2F+%28+5+%2B+25+%29+=+.9+\"$
\n" ); document.write( " $\"+27+%2F+30+=+.9+\"$
\n" ); document.write( " $\"+27+=+.9%2A30+\"$
\n" ); document.write( " $\"+27+=+27+\"$
\n" ); document.write( "OK \n" ); document.write( "

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