document.write( "Question 541630: An investment of $140,000 was made by a business club. The investment was split into three parts and lasted for 1 year. The first part of the invesment earned 8% interest, the second 6%, and the third 9%. Total interest from the investments was $10440. The interest from the first investment was 2 times the interest from the second. Find the amount of the three parts of the investment. What is the amount of the first part of the investment? \n" ); document.write( "
Algebra.Com's Answer #354245 by mananth(16946)\"\" \"About 
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partI x 8 %
\n" ); document.write( "part II y 6 %
\n" ); document.write( "part III z 9 %
\n" ); document.write( "Total Investment=$ 140000
\n" ); document.write( "Total interest from all =$ 10440
\n" ); document.write( "Interest from Part I is 2 times interest from Part II
\n" ); document.write( "
\n" ); document.write( "Interest from part II = 0.06 y
\n" ); document.write( "Interest from partI = 0.08 x =
\n" ); document.write( "Interest from part III= 0.09 z
\n" ); document.write( "0.08 x = 2 * 0.06 y
\n" ); document.write( "0.08 x = 0.12 y
\n" ); document.write( "x= 1.5 y
\n" ); document.write( "0.06 y + 0.08 x + 0.09 z = 10440
\n" ); document.write( "But 0.08 x = 0.12 y
\n" ); document.write( "0.06 y + 0.12 y + 0.09 z = 10440
\n" ); document.write( "0.18 y + 0.09z = 10440 -------------- 1
\n" ); document.write( "
\n" ); document.write( "Investment at
\n" ); document.write( "x+y+z= 140000
\n" ); document.write( "1.5 y+ 1 y + 1 z = 140000
\n" ); document.write( "2.5 y + 1 z = 140000 --------------2
\n" ); document.write( "
\n" ); document.write( "0 y + 0.09 z = 10440 .............1
\n" ); document.write( "2.5 y + 1 z = 140000 .............2
\n" ); document.write( "Eliminate z
\n" ); document.write( "multiply (1)by 1
\n" ); document.write( "Multiply (2) by -0.09
\n" ); document.write( "0.18 y 0.09 z = 10440
\n" ); document.write( "-0.23 y + -0.09 z = -12600
\n" ); document.write( "Add the two equations
\n" ); document.write( "-0.04 y = -2160
\n" ); document.write( "/ -0.04
\n" ); document.write( "y = 48000.00
\n" ); document.write( "plug value of y in (1)
\n" ); document.write( "0.18 y + 0.09 z = 10440
\n" ); document.write( "8640 + 0.09 z = 10440
\n" ); document.write( " 0.09 z = 10440 -8640
\n" ); document.write( " 0.09 z = 1800
\n" ); document.write( " z = 20000.00
\n" ); document.write( "
\n" ); document.write( "x+y+z= 140000
\n" ); document.write( "
\n" ); document.write( "x= 140000 -( 48000 + 20000 )
\n" ); document.write( "x= 72000
\n" ); document.write( "
\n" ); document.write( "CHECK
\n" ); document.write( "
\n" ); document.write( " amount Rate Interest
\n" ); document.write( "x = 72000 8 % 5760
\n" ); document.write( "y= 48000 6 % 2880
\n" ); document.write( "z= 20000 9 % 1800
\n" ); document.write( "Total 140000 10440
\n" ); document.write( "
\n" ); document.write( "m.ananth@hotmail.ca
\n" ); document.write( " \n" ); document.write( "
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