document.write( "Question 726434: A man invests $1200, part at 5% and part at 4% per annum, and his total income is $55.50. How much did he invest at each rate? \n" ); document.write( "
Algebra.Com's Answer #444599 by mananth(16946)\"\" \"About 
You can put this solution on YOUR website!
Part I 5.00% per annum ------------- Amount invested =x
\n" ); document.write( "Part II 4.00% per annum ------------ Amount invested = y
\n" ); document.write( " 1200
\n" ); document.write( "Interest----- 55.50
\n" ); document.write( "
\n" ); document.write( "Part I 5.00% per annum ---x *
\n" ); document.write( "Part II 4.00% per annum ---y
\n" ); document.write( "Total investment
\n" ); document.write( "x + 1 y= 1200 -------------1
\n" ); document.write( "Interest on both investments
\n" ); document.write( "5.00% x + 4.00% y= 55.5
\n" ); document.write( "Multiply by 100
\n" ); document.write( "5 x + 4 y= 5550.00 --------2
\n" ); document.write( "Multiply (1) by -5
\n" ); document.write( "we get
\n" ); document.write( "-5 x -5 y= -6000.00
\n" ); document.write( "Add this to (2)
\n" ); document.write( "0 x -1 y= -450
\n" ); document.write( "divide by -1
\n" ); document.write( " y = 450 - x)
\n" ); document.write( "Part I 5.00% $ 750
\n" ); document.write( "Part II 4.00% $ 450
\n" ); document.write( "
\n" ); document.write( "CHECK
\n" ); document.write( "750 --------- 5.00% ------- 37.50
\n" ); document.write( "450 ------------- 4.00% ------- 18.00
\n" ); document.write( "Total -------------------- 55.50
\n" ); document.write( " \n" ); document.write( "
\n" );