Question 548808
Using matrix calculations, solve the following problem. 
A total of $75,000 is invested in three funds paying 6%, 8%, and 10% simple interest. The yearly interest is $6400. Twice as much money is invested at 10% as is invested at 6%. How much is invested in each of the funds. 
a. set up the 3 linear equations in 3 variables 
Show the 3 linear equations 
s   +    e    +   t   =  75,000
6s  +   8e    + 10t   =  640000
2s  +   0e    -  t    =  0 
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b. put the coefficients into an augmented matrix 
1.....1.....1.....75000
6.....8....10.....640000
2.....0....-1.....0
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c. solve the matrix using any method you like
Put the solution in the box.
s = 20000
e = 15000
t = 40000
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Cheers,
Stan H.