Problema Solution
Solving systems of linear equations in two variables:
Walt made an extra $9000 last year from a part-time job. He invested part of the money at 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%?
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Walt made an extra $9000 last year from a part-time job. He invested part of the money at 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 the money invested for 9% interest be x , so the rest invested at 8% is 9000-x.
Time = 1 year
Simple Interest
FROM 9%= x*9*1/100 = 9x/100
FROM 8% = (9000-x)*8*1/100 = (9000-x)/100
Total interest = 770
9x/100 + (9000-x)/100 = 770
9000 + 8x = 77000
8x = 68000
x = 850