document.write( "Question 1026009: A chemistry teacher needs to mix a 30% salt solution
\n" ); document.write( "with a 70% salt solution to make 20 qt of a 40% salt
\n" ); document.write( "solution. How many quarts of each solution should the
\n" ); document.write( "teacher mix to get the desired result? \n" ); document.write( "

Algebra.Com's Answer #641265 by josmiceli(19441) $\"\"$ $\"About$

You can put this solution on YOUR website!
Let $\"+a+\"$ = quarts of 30% solution needed
\n" ); document.write( "Let $\"+b+\"$ = quarts of 70% solution needed
\n" ); document.write( "---------------------
\n" ); document.write( "(1) $\"+a+%2B+b+=+20+\"$
\n" ); document.write( "(2) $\"+%28+.3a+%2B+.7b+%29+%2F+20+=+.4+\"$
\n" ); document.write( "-------------------------
\n" ); document.write( "(2) $\"+.3a+%2B+.7b+=+8+\"$
\n" ); document.write( "(2) $\"+3a+%2B+7b+=+80+\"$
\n" ); document.write( "Multiply both sides of (1) by $\"+3+\"$
\n" ); document.write( "and subtract (1) from (2)
\n" ); document.write( "----------------------
\n" ); document.write( "(2) $\"+3a+%2B+7b+=+80+\"$
\n" ); document.write( "(1) $\"+-3a+-+3b+=+-60+\"$
\n" ); document.write( "------------------------
\n" ); document.write( " $\"+4b+=+20+\"$
\n" ); document.write( " $\"+b+=+5+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+a+%2B5+=+20+\"$
\n" ); document.write( "(1) $\"+a+=+15+\"$
\n" ); document.write( "------------------
\n" ); document.write( "15 quarts of 30% solution is needed
\n" ); document.write( "5 quarts of 70% solution is needed
\n" ); document.write( "--------------------------------
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+%28+.3a+%2B+.7b+%29+%2F+20+=+.4+\"$
\n" ); document.write( "(2) $\"+%28+.3%2A15+%2B+.7%2A5+%29+%2F+20+=+.4+\"$
\n" ); document.write( "(2) $\"+%28+4.5+%2B+3.5+%29+%2F+20+=+.4+\"$
\n" ); document.write( "(2) $\"+8%2F20+=+.4+\"$
\n" ); document.write( "(2) $\"+8+=+8+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );