document.write( "Question 366383: A health clinic uses a solution of bleach to sterilize petri dishes in which cultures are grown. The sterilization tank contains 120 gal of a solution of 4% ordinary household bleach mixed with pure distilled water. New research indicates that the concentration of bleach should be 6% for complete sterilization. How much of the solution should be drained and replaced with bleach to increase the bleach content to the recommended level? \n" ); document.write( "
Algebra.Com's Answer #261079 by josmiceli(19441)\"\" \"About 
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Let \"x\" = gallons of 4% solution to be drained
\n" ); document.write( "given:
\n" ); document.write( "Bleach in 4% solution:
\n" ); document.write( "\".04%2A120+=+4.8\" gal
\n" ); document.write( "Bleach in removed portion:
\n" ); document.write( "\".04x\"
\n" ); document.write( "Gallons of bleach added:
\n" ); document.write( "\"x\"
\n" ); document.write( "----------
\n" ); document.write( "In words:
\n" ); document.write( "(initial gallons of bleach - bleach removed + bleach added)/(total gallons) = 6%
\n" ); document.write( "\"%284.8+-+.04x+%2B+x%29%2F120+=+.06\"
\n" ); document.write( "\"4.8+-+.04x+%2B+x+=+7.2\"
\n" ); document.write( "\".96x+=+2.4\"
\n" ); document.write( "\"x+=+2.5\"
\n" ); document.write( "2.5 gallons of 4% solution must be drained
\n" ); document.write( "and replaced with pure bleach
\n" ); document.write( "
\n" );