Can someone help me with this? No links please.

If 20% of a number is 35, what is 50% of that number?

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?

Ineed me i stuck and i don’t want to get it wrong