10 a lvorlition. 4. Let e(x) be the string of uppercase letters obtained from a string 2 by replacing each letter in x (plaintext) with the letter given in the following table. 12 N 1 22 plain A B C D E F G H I J K L M N O P Q R S T U V W X Y Z cipher BCD AFGHEJ KLINMP Q ROTU V S X Y Z W (a) Calculate e(ele(e(AMAZING)))). (b) Explain why the result of part (a) holds for any text string r. (c) If d(x) is the decipherment function, find a formula for d(x) in terms of e(x)