I’m really struggling. Can someone help me figure this out?

Which value of c would make he following expression completely factored? 8x+cy

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?

The estimated number of people to attend the last bengals game of the season was 2000. the actual number of fans attending was 1200. by what percent did the estimate differ from the actual?