document.write( "Question 399310: a chemist must mix 8 L of a 40% acid solution with some 70% solution to get a 50% solution. how much of the 70% solution should be used? \n" ); document.write( "

Algebra.Com's Answer #282750 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
(liters of acid in final solution)/(liters of final solution) = 50%
\n" ); document.write( "Acid in 40% solution = $\".4%2A8+=+3.2\"$
\n" ); document.write( "Let $\"x\"$ = liters of 70% solution to use
\n" ); document.write( " $\".7x\"$ = liters of acid in 70% solution
\n" ); document.write( "--------------------------------------------
\n" ); document.write( " $\"%28.7x+%2B+3.2%29%2F%288+%2B+x%29+=+.5\"$
\n" ); document.write( " $\".7x+%2B+3.2+=+.5%2A%288+%2B+x%29\"$
\n" ); document.write( " $\".7x+%2B+3.2+=+4+%2B+.5x\"$
\n" ); document.write( " $\".2x+=+.8\"$
\n" ); document.write( " $\"x+=+4\"$
\n" ); document.write( "4 liters of 70% solution are needed
\n" ); document.write( "check answer:
\n" ); document.write( " $\"%28.7x+%2B+3.2%29%2F%288+%2B+x%29+=+.5\"$
\n" ); document.write( " $\"%28.7%2A4+%2B+3.2%29%2F%288+%2B+4%29+=+.5\"$
\n" ); document.write( " $\"%282.8+%2B+3.2%29+%2F+12+=+.5\"$
\n" ); document.write( " $\"6%2F12+=+.5\"$
\n" ); document.write( " $\".5+=+.5\"$
\n" ); document.write( "OK
\n" ); document.write( " \n" ); document.write( "

\n" );