Question

Helene invested a total of $1,000 in two simple-interest bank accounts. One account paid 6% annual

interest; the other paid 7% annual interest. The total amount of interest she earned after one year was
$66. Enter and solve a system of equations to find the amount invested in each account. Enter the interest
rates in order as given in the problem. (Hint: Change the interest rates into decimals first.)
x+y = 1,000
0.06
x+ 0.07
y = 66
Helene invested $
at 6% and $
at 7%.​

Answer 1

Helene invested $ 400 at 6% and $ 600 at 7%.​

Explanation:

Let

x -----> the amount invested at 6%

y -----> the amount invested at 7%

we know that

The interest earned with the amount invested at 6% plus the interest earned by the amount invested at 7% must be equal to $66

Remember that

`6\%=6/100=0.06\\7\%=7/100=0.07`

so

`x+y=1,000` ----> equation A

`0.06x+0.07y=66` ----> equation B

Solve the system of equations by graphing

The solution of the system is the intersection point both graphs

using a graphing tool

The solution is the point (400,600)

see the attached figure

therefore

Helene invested $ 400 at 6% and $ 600 at 7%.​