document.write( "Question 790273: Tyler McGinnis invested some money at 3% simple interest and some at 5% simple interest. The total amount of his investment was $28,000, and the interest he earned during the first year was $1240. How much did he invest at each rate? \n" ); document.write( "
Algebra.Com's Answer #479107 by mananth(16946)\"\" \"About 
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Part I 3.00% per annum ------------- Amount invested =x
\n" ); document.write( "Part II 5.00% per annum ------------ Amount invested = y
\n" ); document.write( " 28000
\n" ); document.write( "Interest----- 1240.00
\n" ); document.write( "
\n" ); document.write( "Part I 3.00% per annum ---x
\n" ); document.write( "Part II 5.00% per annum ---y
\n" ); document.write( "Total investment
\n" ); document.write( "x + 1 y= 28000 -------------1
\n" ); document.write( "Interest on both investments
\n" ); document.write( "3.00% x + 5.00% y= 1240
\n" ); document.write( "Multiply by 100
\n" ); document.write( "3 x + 5 y= 124000.00 --------2
\n" ); document.write( "Multiply (1) by -3
\n" ); document.write( "we get
\n" ); document.write( "-3 x -3 y= -84000.00
\n" ); document.write( "Add this to (2)
\n" ); document.write( " 2 y= 40000
\n" ); document.write( "divide by 2
\n" ); document.write( " y = 20000 - x)
\n" ); document.write( "Part I 3.00% $ 8000
\n" ); document.write( "Part II 5.00% $ 20000
\n" ); document.write( "
\n" ); document.write( "CHECK
\n" ); document.write( "8000 --------- 3.00% ------- 240.00
\n" ); document.write( "20000 ------------- 5.00% ------- 1000.00
\n" ); document.write( "Total -------------------- 1240.00
\n" ); document.write( "
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