document.write( "Question 778723: Walt made an extra $10,000 last year from a part-time job. He invested part of the money at 7% and the rest at 10%. He made a total of $820 in interest. How much was invested at 10%? \n" ); document.write( "
Algebra.Com's Answer #474900 by mananth(16946)\"\" \"About 
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Part I 7.00% per annum ------------- Amount invested =x
\n" ); document.write( "Part II 10.00% per annum ------------ Amount invested = y
\n" ); document.write( " 10000
\n" ); document.write( "Interest----- 820.00
\n" ); document.write( "
\n" ); document.write( "Part I 7.00% per annum ---x *
\n" ); document.write( "Part II 10.00% per annum ---y
\n" ); document.write( "Total investment
\n" ); document.write( "x + 1 y= 10000 -------------1
\n" ); document.write( "Interest on both investments
\n" ); document.write( "7.00% x + 10.00% y= 820
\n" ); document.write( "Multiply by 100
\n" ); document.write( "7 x + 10 y= 82000.00 --------2
\n" ); document.write( "Multiply (1) by -7
\n" ); document.write( "we get
\n" ); document.write( "-7 x -7 y= -70000.00
\n" ); document.write( "Add this to (2)
\n" ); document.write( "0 x 3 y= 12000
\n" ); document.write( "divide by 3
\n" ); document.write( " y = 4000 - x)
\n" ); document.write( "Part I 7.00% $ 6000
\n" ); document.write( "Part II 10.00% $ 4000
\n" ); document.write( "
\n" ); document.write( "CHECK
\n" ); document.write( "6000 --------- 7.00% ------- 420.00
\n" ); document.write( "4000 ------------- 10.00% ------- 400.00
\n" ); document.write( "Total -------------------- 820.00
\n" ); document.write( "
\n" ); document.write( "m.ananth@hotmail.ca
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