is the subject (cryptography and coding ) considerd as "computer science" or "advanced math"??

Suppose Bob ises RSA cryptosystem. He chooses p = 11,4 -23, ande = 9, 0 his public key ise,c) = (233,99 a) Calculate on). What is Bob's private key? b) Alice wants to send message m = 30 to Bob. Calculate ciphertext that Alice sends to Bob, te) Show how Bob decrypts this ciphertext