Here is the question for my homework:
A mother wants to invest $\$7000.00$ for her son's future education. She invests a portion of the money in a bank certificate of deposit (CD account) which earns $4\%$ and the remainder in a savings bond that earns $7\%$. If the total interest earned after one year is $\$420.00$, how much money was invested in the CD account?
Now, here is my steps:
Amount invested in the savings bond can be represented as $7000 - x$
The interest earned in one year on the CD account is $0.04x$
So, the interest earned on the savings bond in one year can be represented as: $0.07(7000-x)$
The total interested earned after one year is $\$420.00$
The equation is now $0.04x+0.07(7000-x) = 420.00$
Now to SIMPLFY it.
I have this so far
$n - 420 = 0.03x$
How do I get the number $n$?