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 ->  Human-and-algebraic-language -> 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


   

Question 142993: 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 checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
.09X+.08(9,000-X)=770
.09X+720-.08X=770
.01X=770-720
.01X=50
X=50/.01
X=$5,000 FOR THE INVESTMENT @ 9%.
9,000-5,000=$4,000 INVESTED @ 8%.
PROOF:
.09*5,000+.08*4,000=770
450+320=770
770=770