document.write( "Question 973749: pure acid is to be added to a 10%acid solution to obtain 90l of 22% solution .
\n" ); document.write( " what amounts of each should be used? \n" ); document.write( "

Algebra.Com's Answer #595884 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = liters of pure acid needed
\n" ); document.write( "Let $\"+b+\"$ = liters of 10% acid solution needed
\n" ); document.write( " $\"+.1b+\"$ = liters of acid in 10% solution
\n" ); document.write( "-----------------------------
\n" ); document.write( "(1) $\"+%28+a+%2B+.1b+%29+%2F+90+=+.22+\"$
\n" ); document.write( "(2) $\"+a+%2B+b+=+90+\"$
\n" ); document.write( "---------------------
\n" ); document.write( "(1) $\"+a+%2B+.1b+=+19.8+\"$
\n" ); document.write( "---------------------
\n" ); document.write( "Subtract (1) from (2)
\n" ); document.write( "(2) $\"+a+%2B+b+=+90+\"$
\n" ); document.write( "(1) $\"+-a+-+.1b+=+-19.8+\"$
\n" ); document.write( "----------------------
\n" ); document.write( " $\"+.9b+=+70.2+\"$
\n" ); document.write( " $\"+b+=+78+\"$
\n" ); document.write( "and
\n" ); document.write( "(2) $\"+a+%2B+78+=+90+\"$
\n" ); document.write( "(2) $\"+a+=+12+\"$
\n" ); document.write( "12 liters of pure acid are needed
\n" ); document.write( "78 liters of 10% acid solution are needed
\n" ); document.write( "--------------------------------------
\n" ); document.write( "check:
\n" ); document.write( "(1) $\"+%28+a+%2B+.1b+%29+%2F+90+=+.22+\"$
\n" ); document.write( "(1) $\"+%28+12+%2B+.1%2A78+%29+%2F+90+=+.22+\"$
\n" ); document.write( "(1) $\"+%28+12+%2B+7.8+%29+%2F+90+=+.22+\"$
\n" ); document.write( "(1) $\"+19.8+=+.22%2A90+\"$
\n" ); document.write( "(1) $\"+19.8+=+19.8+\"$
\n" ); document.write( "OK\r
\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "

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