PLEASE HELP. very urgent, what’s the answer

Closing a credit card usually _your debt ratio. a. increasesb. decreasesc. improvesd. has no effect on

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?

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.