document.write( "Question 755841: A hospital staff mixed a 75% disinfectant solution with a 25% disinfectant solution. How many liters of each were used to make 25L of a 35% disinfectant solution? \n" ); document.write( "

Algebra.Com's Answer #459855 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = liters of 75% solution needed
\n" ); document.write( "Let $\"+b+\"$ = liters of 25% solution needed
\n" ); document.write( " $\"+.75a+\"$ = liters of disinfectant in 75% solution
\n" ); document.write( " $\"+.25a+\"$ = liters of disinfectant in 25% solution
\n" ); document.write( "-------------------
\n" ); document.write( "given:
\n" ); document.write( "(1) $\"+a+%2B+b+=+25+\"$
\n" ); document.write( "(2) $\"+%28+.75a+%2B+.25b+%29+%2F+25+=+.35+\"$
\n" ); document.write( "-----------------------------
\n" ); document.write( "(2) $\"+.75a+%2B+.25b+=+.35%2A25+\"$
\n" ); document.write( "(2) $\"+.75a+%2B+.25b+=+8.75+\"$
\n" ); document.write( "(2) $\"+75a+%2B+25b+=+875+\"$
\n" ); document.write( "Multiply both sides of (1) by $\"+25+\"$ and
\n" ); document.write( "subtract (1) from (2)
\n" ); document.write( "(2) $\"+75a+%2B+25b+=+875+\"$
\n" ); document.write( "(1) $\"+-25a+-+25b+=+-625+\"$
\n" ); document.write( " $\"+50a+=+250+\"$
\n" ); document.write( " $\"+a+=+5+\"$
\n" ); document.write( "and, since
\n" ); document.write( "(1) $\"+a+%2B+b+=+25+\"$
\n" ); document.write( "(1) $\"+5+%2B+b+=+25+\"$
\n" ); document.write( "(1) $\"+b+=+20+\"$
\n" ); document.write( "5 liters of 75% solution are needed
\n" ); document.write( "20 liters of 25% solution are needed
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+%28+.75a+%2B+.25b+%29+%2F+25+=+.35+\"$
\n" ); document.write( "(2) $\"+%28+.75%2A5+%2B+.25%2A20+%29+%2F+25+=+.35+\"$
\n" ); document.write( "(2) $\"+%28+3.75+%2B+5+%29+%2F+25+=+.35+\"$
\n" ); document.write( "(2) $\"+8.75+=+.35%2A25+\"$
\n" ); document.write( "(2) $\"+8.75+=+8.75+\"$
\n" ); document.write( "OK \n" ); document.write( "

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