document.write( "Question 799144: Blair needs a 25% acid solution for an experiment in class, but unfortunately, he only has a 15% solution in the stockroom. How much pure acid must he add to 80 litres of a 15% acid solution to bring it up to a concentration of 25%? \n" ); document.write( "

Algebra.Com's Answer #482520 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"+x+\"$ = liters of pure acid needed
\n" ); document.write( " $\"+.15%2A80+=+12+\"$ liters of acid in 15% solution
\n" ); document.write( "---------------
\n" ); document.write( " $\"+%28+12+%2B+x+%29+%2F+%28+80+%2B+x+%29+=+.25+\"$
\n" ); document.write( " $\"+12+%2B+x+=+.25%2A%28+80+%2B+x+%29+\"$
\n" ); document.write( " $\"+12+%2B+x+=+20+%2B+.25x+\"$
\n" ); document.write( " $\"+.75x+=+8+\"$
\n" ); document.write( " $\"+x+=+8%2F.75+\"$
\n" ); document.write( " $\"+x+=+10.667+\"$
\n" ); document.write( "10.667 liters od pure acid must be added
\n" ); document.write( "check:
\n" ); document.write( " $\"+%28+12+%2B+x+%29+%2F+%28+80+%2B+x+%29+=+.25+\"$
\n" ); document.write( " $\"+%28+12+%2B+10.667+%29+%2F+%28+80+%2B+10.667+%29+=+.25+\"$
\n" ); document.write( " $\"+22.667+%2F+90.667+=+.25+\"$
\n" ); document.write( " $\"+22.667+=+.25%2A90.667+\"$
\n" ); document.write( " $\"+22.667+=+22.667+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );