I have a question how do you solve a proportion divide or multiply???

Isee the amount was $90.00 then reduced to $75.00 , what is the percent ?

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?

Anew movie is released each year for 14 years to go along with a popular book series. each movie is 2 minutes longer than the last to go along with a plot twist. the first movie is 70 minutes long. use an arithmetic series formula to determine the total length of all 14 movies