Liza deposits money at 2.5% interest, with twice as much deposited at 3.5%. Find the amount deposited at each rate if the total annual interest income is $1520

Solution:
1. Let the amount deposited at 2.5% be x.
2. The amount deposited at 3.5% is twice the amount at 2.5%, which is 2x.
3. The annual interest from the amount deposited at 2.5% is:
0.025x
4. The annual interest from the amount deposited at 3.5% is:
0.035 \cdot 2x = 0.07x
5. The total interest from both deposits is:
0.025x + 0.07x = 0.095x
6. We know that the total interest is given as USD 1520. Therefore, the equation is:
0.095x = 1520
7. Solve for x:
x = \frac{1520}{0.095}
x = 16000
8. The amount deposited at 2.5% is x = 16000 USD.
9. The amount deposited at 3.5% is 2x = 32000 USD.

Answer:
The amount deposited at 2.5% is USD 16000, and the amount deposited at 3.5% is USD 32000.