SOLUTION: Can somebody help me please? I can't figure this out. 3. Walt made an extra $9000 last year from a part-time job. He invested part of the money at 9% and the rest at 8%. He made

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Question 154013This question is from textbook elementary and intermediate algebra concepts and applications
: Can somebody help me please? I can't figure this out.
3. Walt made an extra $9000 last year from a part-time job. He invested part of the money at 9% and the rest at 8%. He made a total of $770 in interest. How much was invested at 8%?
This question is from textbook elementary and intermediate algebra concepts and applications

Answer by nerdybill(7384) About Me  (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 9% and the rest at 8%. He made a total of $770 in interest. How much was invested at 8%?
.
Let x = amount invested at 8%
then
9000-x = amount invested at 9%
.
Our formula is then:
.08x + .09(9000-x) = 770
.08x + 810 - .09x = 770
810 - .01x = 770
810 = 770 + .01x
40 = .01x
$4000 = x