Final answer:
To calculate the change in stock value over seven weeks with a weekly decrease of $3, multiply the decrease by the number of weeks: $3/week × 7 weeks equals to a total decrease of $21.
Step-by-step explanation:
The question presents a scenario where the value of a stock decreases by a certain amount each week over a period. Specifically, the value of the stock went down $3 each week for a period of seven weeks. To describe the change in the value of the stock at the end of the seven-week period, we need to calculate the total decrease in value.
To find the total decrease in value over seven weeks, we simply multiply the weekly decrease by the number of weeks:
- Weekly decrease in value: $3
- Number of weeks: 7
- Total decrease in value: $3/week × 7 weeks = $21
Therefore, the change in the value of the stock at the end of the seven-week period is a decrease of $21, which corresponds to option A.