Explain why not all encryptors have corresponding decryptors, providing at least two examples of cncryptors wihch cannot be decrypted.

of the (26)^2=676 possible encryptors, determine precisely which have decryptors and which don't. How many decryptable encryptors are there?

Explain a procedure indicating how to find a decryptor, that is, if one exists for any given encryptor

Help would be greatly appreciated

For these problems we are using linear congruences. A linear encryptor is a function of the form E(w)=Aw+B (mod N)