document.write( "Question 170500: I have 3 oz. of an 80% solution of weed killer. How much pure water must i add to get a 20% solution? \n" ); document.write( "

Algebra.Com's Answer #125885 by josmiceli(19441) $\"\"$ $\"About$

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In words:
\n" ); document.write( "(amount of weed killer) / (weed killer + H2O) = % solution
\n" ); document.write( "I start with 3 oz of 80% solution. In this 3 oz, there is
\n" ); document.write( " $\".8%2A3+=+2.4\"$ oz of weed killer.
\n" ); document.write( "Let $\"x\"$ = amount of water to be added
\n" ); document.write( "I'm not adding weed killer, just water, so
\n" ); document.write( " $\"2.4+%2F+%28x+%2B+3%29+=+.2\"$
\n" ); document.write( "Multiply both sides by $\"x+%2B+3\"$
\n" ); document.write( " $\"2.4+=+.2%2A%28x+%2B+3%29\"$
\n" ); document.write( " $\"2.4+=+.2x+%2B+.6\"$
\n" ); document.write( " $\".2x+=+1.8\"$
\n" ); document.write( " $\"x+=+9\"$
\n" ); document.write( "9 oz of water must be added to get a 20% solution
\n" ); document.write( "check:
\n" ); document.write( " $\"2.4+%2F%289+%2B+3%29+=+.2\"$
\n" ); document.write( " $\"2.4%2F12+=+.2\"$
\n" ); document.write( " $\".2+=+.2\"$
\n" ); document.write( "OK \n" ); document.write( "

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