Given:
Total amount invested = $3000
Rate of annul interest on investments are 5% and 8%.
Total interest earned for the year = $210
To find:
The amount invested at each rate.
Solution:
Let the amount invested at 5% be
and the amount invested at 8% be
.
Total interest earned for the year = $210
It means. 5% of
+ 8% of
= 210
![x* (5)/(100)+(3000-x)* (8)/(100)=210](https://img.qammunity.org/2022/formulas/mathematics/high-school/qa8j8xtihh0zc1htx2kb5pvfz5lz8p5nxf.png)
Multiply both sides by 100.
![5x+(3000-x)8=21000](https://img.qammunity.org/2022/formulas/mathematics/high-school/mp1y3yfe9888s89zg8vpa17ffr2g0hwoxz.png)
![5x+24000-8x=21000](https://img.qammunity.org/2022/formulas/mathematics/high-school/5cx09ruvk0tzuyxn8qtusmff0l5lc51vqf.png)
![-3x=21000-24000](https://img.qammunity.org/2022/formulas/mathematics/high-school/axk6hqloc2gdn38tzkefg9m6vsi4u20fu9.png)
![-3x=-3000](https://img.qammunity.org/2022/formulas/mathematics/high-school/ev150dfkgxct0y4np0v4uix7c4e6kk3cpy.png)
Divide both sides by -3.
![x=1000](https://img.qammunity.org/2022/formulas/mathematics/high-school/uyhrf3thrd730ek7nfji27fvmzy367n4xp.png)
Now,
![3000-x=3000-1000](https://img.qammunity.org/2022/formulas/mathematics/high-school/2nwf85lc74axz2708j6kydje1y4jlpogod.png)
![3000-x=2000](https://img.qammunity.org/2022/formulas/mathematics/high-school/qsv5mdvuu73ce87bjgsn6cten1ww2svo4p.png)
Therefore, the amount invested at the rate of 5% is $1000 and the amount invested at the rate of 8% is $2000.