SOLUTION: Last year, Carlos had 20000 to invest. He invested some of it in an account that paid 9% simple interest per year, and he invested the rest in an account that paid 5% simple inte
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Question 783102: Last year, Carlos had 20000 to invest. He invested some of it in an account that paid 9% simple interest per year, and he invested the rest in an account that paid 5% simple interest per year. After one year, he received a total of 1160 in interest. How much did he invest in each account?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
Part I 9.00% per annum ------------- Amount invested =x
Part II 5.00% per annum ------------ Amount invested = y
20000
Interest----- 1160.00
Part I 9.00% per annum ---x
Part II 5.00% per annum ---y
Total investment
x + 1 y= 20000 -------------1
Interest on both investments
9.00% x + 5.00% y= 1160
Multiply by 100
9 x + 5 y= 116000.00 --------2
Multiply (1) by -9
we get
-9 x -9 y= -180000.00
Add this to (2)
0 x -4 y= -64000
divide by -4
y = 16000 - x)
Part I 9.00% $ 4000
Part II 5.00% $ 16000
CHECK
4000 --------- 9.00% ------- 360.00
16000 ------------- 5.00% ------- 800.00
Total -------------------- 1160.00
m.ananth@hotmail.ca
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