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 end of

Algebra ->  Customizable Word Problem Solvers  -> Finance -> 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 end of      Log On

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Question 112312: 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 checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
.08X+.09(9000-X)=770
.08X+810-.09X=770
-.01X=770-810
-.01X=-40
X=-40/-.01
X=4000 AMOUNT INVESTED @ 8%
9000-4000=5000 INVESTED @ 9%
PROOF
.08*4000+.09*5000=770
320+450=770
770=770