If numbers are considered like terms, why are letters not considered like terms?

Write the sine and cosine values of a, b, respectively, in the figure for (1) and (2) + explanation.

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?

Whats is the value of the variables ?