document.write( "Question 565904: A college student earned $8100 during the summer. They invested part of the money at 8% and the rest at 6%. If they received a total of $564 in interest at the end of the year how much was invested at 8%?  \n" ); document.write( "
Algebra.Com's Answer #366006 by mananth(16946)\"\" \"About 
You can put this solution on YOUR website!
Investment I 8.00% per annum ----x
\n" ); document.write( "Investment II 6.00% per annum ----y
\n" ); document.write( "The sum of the investments is $8,100.00
\n" ); document.write( "The sum of individual interests = $564.00
\n" ); document.write( "x + y 8100 ------------------------1
\n" ); document.write( "8.00% x + 6.00% y = $564.00
\n" ); document.write( "Multiply by 100
\n" ); document.write( "8 x + 6 y = $56,400.00--------2
\n" ); document.write( "
\n" ); document.write( "Multiply (1) by -8
\n" ); document.write( "we get
\n" ); document.write( "
\n" ); document.write( "-8x-8y= -64800.00
\n" ); document.write( "
\n" ); document.write( "Add this to (2)
\n" ); document.write( "
\n" ); document.write( "0x-2y=-$8,400.00
\n" ); document.write( "
\n" ); document.write( "divide by-2
\n" ); document.write( "
\n" ); document.write( "y = $4,200.00 investment at 6.00%
\n" ); document.write( "Balance $3,900.00 investment at 8.00%
\n" ); document.write( "CHECK
\n" ); document.write( "$3,900.00 $312.00
\n" ); document.write( "$4,200.00 $252.00
\n" ); document.write( "Total $564.00
\n" ); document.write( " \n" ); document.write( "
\n" );