Explain me how to do it pls I need help

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?

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?

Im literally having a mental breakdown