Can the common difference in an arithmetic sequence be negative

Martha needs 22.25 strawberries for every 5 smoothies she makes. complete the table to see how many strawberries she would need to make 10 smoothies and 20 smoothies.

Just tell me how to set up the equation.

Recall that the owner of a local health food store recently started a new ad campaign to attract more business and wants to know if average daily sales have increased. historically average daily sales were approximately $2,700. the upper bound of the 95% range of likely sample means for this one-sided test is approximately $2,843.44. if the owner took a random sample of forty-five days and found that daily average sales were now $2,984, what can she conclude at the 95% confidence level?