document.write( "Question 128549: A man has $20,000 invested at 7% and %50,000 invested at 4% simple interest. What additional sum must he invest at 6% to give him an overall return of 5%? \n" ); document.write( "

Algebra.Com's Answer #94067 by josmiceli(19441) $\"\"$ $\"About$

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overall percent gain = (sum of separate gains) / (total amount invested)
\n" ); document.write( " $\"%28.07%2A20000+%2B+.04%2A50000++%2B+.06%2Ax%29+%2F+%2820000+%2B+50000+%2B+x%29+=+.05\"$
\n" ); document.write( " $\"%281400+%2B+2000+%2B+.06%2Ax%29+%2F+%2870000+%2B+x%29+=+.05\"$
\n" ); document.write( "multiply both sides by $\"70000+%2B+x\"$
\n" ); document.write( " $\"3400+%2B+.06x+=+.05%2870000+%2B+x%29\"$
\n" ); document.write( " $\"3400+%2B+.06x+=+3500+%2B+.05x\"$
\n" ); document.write( " $\".01x+=+100\"$
\n" ); document.write( " $\"x+=+100%2F.01\"$
\n" ); document.write( " $\"x+=+10000\"$
\n" ); document.write( "He must invest $10,000 at 6% to have an overall return of 5%
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