Can someone help me, please I don't remember how to do this

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?

Dots sells a total of 279 t-shirts ($2) and shorts ($4). in april total sales were $670. how many t-shirts and shorts did dots sell?

If 7x=9y, y/z = 7/5 , then x/z = (a) 2/7 (b) 7/9 (c) 9/5 (d) 9/7 (e) 5/9