document.write( "Question 820681: Joe invests $6000, part at 5% interest and the rest at 7%. If his annual interest income is $372, how much did he invest at each rate? \n" ); document.write( "

Algebra.Com's Answer #493690 by mananth(16946) $\"\"$ $\"About$

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Part I 5.00% per annum ------------- Amount invested =x
\n" ); document.write( "Part II 7.00% per annum ------------ Amount invested = y
\n" ); document.write( " 6000
\n" ); document.write( "Interest----- 372.00
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\n" ); document.write( "Part I 5.00% per annum ---x
\n" ); document.write( "Part II 7.00% per annum ---y
\n" ); document.write( "Total investment
\n" ); document.write( "x + 1 y= 6000 -------------1
\n" ); document.write( "Interest on both investments
\n" ); document.write( "5.00% x + 7.00% y= 372
\n" ); document.write( "Multiply by 100
\n" ); document.write( "5 x + 7 y= 37200.00 --------2
\n" ); document.write( "Multiply (1) by -5
\n" ); document.write( "we get
\n" ); document.write( "-5 x -5 y= -30000.00
\n" ); document.write( "Add this to (2)
\n" ); document.write( "0 x 2 y= 7200
\n" ); document.write( "divide by 2
\n" ); document.write( " y = 3600
\n" ); document.write( "Part I 5.00% $ 2400
\n" ); document.write( "Part II 7.00% $ 3600
\n" ); document.write( "
\n" ); document.write( "CHECK
\n" ); document.write( "2400 --------- 5.00% ------- 120.00
\n" ); document.write( "3600 ------------- 7.00% ------- 252.00
\n" ); document.write( "Total -------------------- 372.00
\n" ); document.write( "
\n" ); document.write( "m.ananth@hotmail.ca
\n" ); document.write( " \n" ); document.write( "

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