13.) 13y² + 9y + 4y² - 31y 14.) 10m²n + 7mn² - m²n
15.) Find the sum of 16y² and -5y²
16.) Find the difference of 10x²y and 2x²y

I will give brainliest

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?