document.write( "Question 724061: Sergio invests part of his 90,000 PESOS at 4% and the rest at 3%. How much money is invested at each rate if he makes a total income of 3,100 PESOS annually? \n" ); document.write( "
Algebra.Com's Answer #443566 by mananth(16946)\"\" \"About 
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Part I 3.00% per annum ------------- Amount invested =x
\n" ); document.write( "Part II 4.00% per annum ------------ Amount invested = y
\n" ); document.write( " 90000
\n" ); document.write( "Interest----- 3100
\n" ); document.write( "
\n" ); document.write( "Part I 3.00% per annum ---x *
\n" ); document.write( "Part II 4.00% per annum ---y
\n" ); document.write( "Total investment
\n" ); document.write( "x + 1 y= 90000 -------------1
\n" ); document.write( "Interest on both investments
\n" ); document.write( "3.00% x + 4.00% y= 3100
\n" ); document.write( "Multiply by 100
\n" ); document.write( "3 x + 4 y= 310000.00 --------2
\n" ); document.write( "Multiply (1) by -3
\n" ); document.write( "we get
\n" ); document.write( "-3 x -3 y= -270000.00
\n" ); document.write( "Add this to (2)
\n" ); document.write( "0 x 1 y= 40000
\n" ); document.write( "divide by 1
\n" ); document.write( "y = 40000
\n" ); document.write( "Part I 3.00% pesos 50000
\n" ); document.write( "Part II 4.00% pesos 40000
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