SOLUTION: You must state your answer in words. You must set up a system of two equations in two variables. You must state what the variables represent. You must show all the steps in solvi

Question 193431This question is from textbook
: You must state your answer in words. You must set up a system of two equations in two variables.
You must state what the variables represent.
You must show all the steps in solving the system of equations.
Heather made an extra $12,000 last year from a part-time job. She invested part of the money at 7% and the rest at 9%. She made a total of $970 in interest. How much was invested at 7%? Thank You! This question is from textbook

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Heather made an extra $12,000 last year from a part-time job. She invested part of the money at 7% and the rest at 9%. She made a total of $970 in interest. How much was invested at 7%?
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Equations:
Quantity Eq: S + N = 12000
Interest Eq:0.07S + 0.09N = 970
----------------------
Multiply thru the 1st equation by 0.07
0.07S + 0.07N = 0.07*12000
0.07S + 0.09N = 970
----------------------------
Subtract to solve for "N":
0.02N = 970 - 0.07*12000
N = $6500
----
S = 12000 - 6500 = $5500 (amt. invested at 7%
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Cheers,
Stan H.

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