need typed solution

15. [4 marks] [3] Find an inverse at 2 module 1? that is between I] and 1?. [bl Using the answer for part [a], spice the cpngruence 2:: E It {mad 1?}. Find a selutic-n her at that is between i] and 1?. 1?. [4 marks] Suppose Alice has her public key P; and her private key 51:; and Ebb has his public key Pa and his private keyr 53, as part of the REA public key cryptbsystem. Alice wants to send a message M to Bob so that he knows for sure that she sent it. Describe what Alice dues and what Bab dues