Help me please this is confusing

If x = 12 and y = 3, what is the value of x - y 2? 81 6 3 18

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?

Linda loans her friend $250 with a 5% monthly intrest rate. how much was the whole loan?