document.write( "Question 775269: Alberto invested $15000, part at 6.5% annual interest and rest at 9%. If his annual income from both investments was $1200, how much was invested at each rate? \n" ); document.write( "

Algebra.Com's Answer #472771 by mananth(16946) $\"\"$ $\"About$

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Part I 6.50% per annum ------------- Amount invested =x
\n" ); document.write( "Part II 9.00% per annum ------------ Amount invested = y
\n" ); document.write( " 15000
\n" ); document.write( "Interest----- 1200.00
\n" ); document.write( "
\n" ); document.write( "Part I 6.50% per annum ---x
\n" ); document.write( "Part II 9.00% per annum ---y
\n" ); document.write( "Total investment
\n" ); document.write( "x + 1 y= 15000 -------------1
\n" ); document.write( "Interest on both investments
\n" ); document.write( "6.50% x + 9.00% y= 1200
\n" ); document.write( "Multiply by 100
\n" ); document.write( "6.5 x + 9 y= 120000.00 --------2
\n" ); document.write( "Multiply (1) by -6.5
\n" ); document.write( "we get
\n" ); document.write( "-6.5 x -6.5 y= -97500.00
\n" ); document.write( "Add this to (2)
\n" ); document.write( "0 x 2.5 y= 22500
\n" ); document.write( "divide by 2.5
\n" ); document.write( " y = 9000
\n" ); document.write( "Part I 6.50% $ 6000
\n" ); document.write( "Part II 9.00% $ 9000
\n" ); document.write( "
\n" ); document.write( "CHECK
\n" ); document.write( "6000 --------- 6.50% ------- 390.00
\n" ); document.write( "9000 ------------- 9.00% ------- 810.00
\n" ); document.write( "Total -------------------- 1200.00
\n" ); document.write( "
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