SOLUTION: Walt made an extra $9000 last year from a part-time job. He invested part of the
money at a 9% annual rate of interest, and the rest at an 8% annual rate of
interest. At the en
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-> SOLUTION: Walt made an extra $9000 last year from a part-time job. He invested part of the
money at a 9% annual rate of interest, and the rest at an 8% annual rate of
interest. At the en
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Question 143318: Walt made an extra $9000 last year from a part-time job. He invested part of the
money at a 9% annual rate of interest, and the rest at an 8% annual rate of
interest. At the end of the year, he made a total of $770 in interest. How much was invested at 8%? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! Walt made an extra $9000 last year from a part-time job. He invested part of the money at a 9% annual rate of interest, and the rest at an 8% annual rate of interest. At the end of the year, he made a total of $770 in interest. How much was invested at 8%?
:
Let x = amt invested at 8%
It said the total amt was 9000, therefore:
(9000-x) = amt invested at 9%
:
An equation showing the sum of the two interest amts to be $770
.08x + .09(9000-x) = 770
;
.08x + 810 - .09x = 770
:
.08x - .09x = 770 - 810
:
-.01x = -40
x =
x = $4000 invested at 8%
;
:
Check solution (5000 invested at 9%)
.08(4000) + .09(5000) =
320 + 450 = 770
