document.write( "Question 996276: A 3% saline solution is combined with a 5% saline solution to form 10 ounces of a 3.8% saline solution. How many ounces of the 3% solution are used? \n" ); document.write( "

Algebra.Com's Answer #614770 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+a+\"$ = ounces of the 3% solution needed
\n" ); document.write( "Let $\"+b+\"$ = ounces of the 5% solution needed
\n" ); document.write( "-----------------------
\n" ); document.write( "(1) $\"+a+%2B+b+=+10+\"$
\n" ); document.write( "(2) $\"+%28+.03a+%2B+.05b+%29+%2F+10+=+.038+\"$
\n" ); document.write( "------------------------------
\n" ); document.write( "(2) $\"+.03a+%2B+.05b+=+.38+\"$
\n" ); document.write( "(2) $\"+3a+%2B+5b+=+38+\"$
\n" ); document.write( "--------------------
\n" ); document.write( "Multiply both sides of (1) by $\"+3+\"$ and
\n" ); document.write( "subtract (1) from (2)
\n" ); document.write( "(2) $\"+3a+%2B+5b+=+38+\"$
\n" ); document.write( "(1) $\"+-3a+-+3b+=+-30+\"$
\n" ); document.write( "--------------------
\n" ); document.write( " $\"+2b+=+8+\"$
\n" ); document.write( " $\"+b+=+4+\"$
\n" ); document.write( "and
\n" ); document.write( "(1) $\"+a+%2B+b+=+10+\"$
\n" ); document.write( "(1) $\"+a+%2B+4+=+10+\"$
\n" ); document.write( "(1) $\"+a+=+6+\"$
\n" ); document.write( "6 ounces of the 3% solution are needed
\n" ); document.write( "---------------
\n" ); document.write( "check:
\n" ); document.write( "(2) $\"+%28+.03a+%2B+.05b+%29+%2F+10+=+.038+\"$
\n" ); document.write( "(2) $\"+%28+.03%2A6+%2B+.05%2A4+%29+%2F+10+=+.038+\"$
\n" ); document.write( "(2) $\"+%28+.18+%2B+.2+%29+%2F+10+=+.038+\"$
\n" ); document.write( "(2) $\"+.38+=+10%2A.038+\"$
\n" ); document.write( "(2) $\"+.38+=+.38+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );