document.write( "Question 629837: What quantity of pure acid must be added to 400 mL of a 40% acid solution to produce a 75% acid solution \n" ); document.write( "

Algebra.Com's Answer #396547 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"x\"$ = ml of pure acid needed
\n" ); document.write( " $\"+.4%2A400+=+160+\"$ ml of acid in 40% solution
\n" ); document.write( " $\"+%28+x+%2B+160+%29+%2F+%28+x+%2B+400+%29+=+.75+\"$
\n" ); document.write( " $\"+x+%2B+160+=+.75%2A%28+x+%2B+400+%29+\"$
\n" ); document.write( " $\"+x+%2B+160+=+.75x+%2B+300+\"$
\n" ); document.write( " $\"+.25x++=+140+\"$
\n" ); document.write( " $\"+x+=+560++\"$
\n" ); document.write( "560 ml of pure acid must be added
\n" ); document.write( "check:
\n" ); document.write( " $\"+%28+x+%2B+160+%29+%2F+%28+x+%2B+400+%29+=+.75+\"$
\n" ); document.write( " $\"+%28+560+%2B+160+%29+%2F+%28+560+%2B+400+%29+=+.75+\"$
\n" ); document.write( " $\"+720+%2F+960+=+.75+\"$
\n" ); document.write( " $\"+720+=+.75%2A960+\"$
\n" ); document.write( " $\"+720+=+720+\"$
\n" ); document.write( "OK \n" ); document.write( "

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