document.write( "Question 997875: how many litres of 50% alchol solution must be mixed with 90 liters of 80% solution to get a 70% soulton \n" ); document.write( "

Algebra.Com's Answer #615837 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"+x+\"$ = liters of 50% alcohol needed
\n" ); document.write( " $\"+.5x+\"$ = liters of alcohol in 50% solution
\n" ); document.write( " $\"+.8%2A90+=+72+\"$ liters of alcohol in 80% solution
\n" ); document.write( "-------------------
\n" ); document.write( " $\"+%28+.5x+%2B+72+%29+%2F+%28+x+%2B+90+%29+=+.7+\"$
\n" ); document.write( " $\"+.5x+%2B+72+=+.7%2A%28+x+%2B+90+%29+\"$
\n" ); document.write( " $\"+.5x+%2B+72+=+.7x+%2B+63+\"$
\n" ); document.write( " $\"+.2x+=+9+\"$
\n" ); document.write( " $\"+x+=+45+\"$
\n" ); document.write( "45 liters of 50% alcohol are needed
\n" ); document.write( "------------------
\n" ); document.write( "check:
\n" ); document.write( " $\"+%28+.5x+%2B+72+%29+%2F+%28+x+%2B+90+%29+=+.7+\"$
\n" ); document.write( " $\"+%28+.5%2A45+%2B+72+%29+%2F+%28+45+%2B+90+%29+=+.7+\"$
\n" ); document.write( " $\"+%28+22.5+%2B+72+%29+%2F+135+=+.7+\"$
\n" ); document.write( " $\"+94.5+=+.7%2A135+\"$
\n" ); document.write( " $\"+94.5+=+94.5+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );