Given ciphertext encrypted using an affine cipher Cpapbmod26

Given ciphertext encrypted using an affine cipher C(p)=(ap+b)mod26 we can use P(c)=a(cb)mod26 (where a is such that aa=1mod26) to recover the plaintext. Consider the ciphertext CUAAUBMVHLCQ encrypted using C(p)=(17p+22)mod26. Give the appropriate decryption function,P, and the plaintext (original message).

Solution