Jeremiah has $40, and Sonita has $20. Jeremiah is saving $5 per week, and Sonita is saving $10 per week. How many weeks do they need to save before they have the same amount of money?

Solution:
1. Initial amounts:
- Jeremiah: USD 40
- Sonita: USD 20

2. Weekly savings:
- Jeremiah: USD 5 per week
- Sonita: USD 10 per week

3. Let the number of weeks be w.

4. Amount after w weeks:
- Jeremiah: 40 + 5w
- Sonita: 20 + 10w

5. Set the amounts equal to find w:
40 + 5w = 20 + 10w

6. Solve for w:
40 + 5w - 5w = 20 + 10w - 5w
40 = 20 + 5w
40 - 20 = 5w
20 = 5w
w = \frac{20}{5} = 4

7. Therefore, they need to save for 4 weeks before they have the same amount of money.

Answer: w = 4