Can someone please give me a mini lesson on proofs. I so don't understand it fully and would love if someone could maybe make it a little easier to understand. Thank you for whoever takes this on.

Simplify this expression.2(10) + 2(x – 4) a. 2x + 16 b. x + 12 c. 2x + 12 d. x + 16

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?

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?