Question

last year, Jessica had 10,000 to invest. She invested some of it in an account that paid 8% simple interest 3 year, and she invested the rest in an account that paid 6% simple interest per year. After one year, she received a total of $780 in interest. How much did she invest in each account?

Answer 1

You need to establish a system of equations to solve this problem.

The first one is

`x+y=10000\text{ ------- (1)}`

Where x and y are the values invested in the two different accounts

The second equation is:

`x\cdot0.08+y\cdot0.06=780\text{ ------- (2)}`

Now, from equation (1) you need to clear y, as follows:

`\begin{gathered} x+y=10000\text{ subtract x from both sides} \\ x+y-x=10000-x \\ y=10000-x \end{gathered}`

Now, replace y into equation (2):