SOLUTION: You invested $7000 in two accounts paying 7% and 6% annual interest, respectively. If the total interest earned for the year was $436, how much was invested at each rate? Part

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Question 783267: You invested $7000 in two accounts paying 7% and 6% annual interest, respectively. If the total interest earned for the year was $436, how much was invested at each rate?
Part 1: Let \,x denote the amount of money invested at 7%. Find an expression in terms of x for the amount invested at 6%.

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Part I 7.00% per annum ------------- Amount invested =x
Part II 6.00% per annum ------------ Amount invested = y
7000
Interest----- 436.00

Part I 7.00% per annum ---x
Part II 6.00% per annum ---y
Total investment
x + 1 y= 7000 -------------1
Interest on both investments
7.00% x + 6.00% y= 436
Multiply by 100
7 x + 6 y= 43600.00 --------2
Multiply (1) by -7
we get
-7 x -7 y= -49000.00
Add this to (2)
0 x -1 y= -5400
divide by -1
y = 5400 - x)
Part I 7.00% $ 1600
Part II 6.00% $ 5400

CHECK
1600 --------- 7.00% ------- 112.00
5400 ------------- 6.00% ------- 324.00
Total -------------------- 436.00