How can you decompose 6/4

Janet drove 300 miles in 4.5 hours. write an equation to find the rate at which she was traveling

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?

Me d is also an option but i couldn't get it in the picture