For all the remaining questions, you will work with the following toy encryption scheme. It encrypts plaintexts that consist of only uppercase letters and the underscore character (27 characters total):

ABCDEFGHIJKLMNOPQRSTUVWXYZ_

Note that the underscore character is part of the alphabet and will also be encrypted. A key in this scheme consists of 4 digits, each from 0 to 9. Each digit tells how much to shift one character, that is, change it to the character that many positions later in the alphabet. If the shift goes past '_', then we wrap around to the beginning.

The key is applied separately to each group of 4 letters in the message. For example, if the message HI_SALLY is encrypted with the key 2407, the H would be shifted by 2, the I by 4, the underscore by 0, and the S by 7. Then we would start over with the first digit of the key, shifting A by 2, L by 4, and so on. So the ciphertext would be: JM_ZCPLE.

1. (3 pts) Give the encryption of the following messages with the key 3654.
2. 1. SELL_GME

2. FRANZ_IS_MOLE

3. DEPLOY_ALL_DIVISIONS

2. (3 pts) Give the decryption of the following messages that have been encrypted with the key 4127.
   1. FV_GQPAPPMC

2. EOFEDJUGTMCUX

3. _JVOHSCCDVPPXT

3. (5 pts) Rewrite the above description of how to encrypt and decrypt in this scheme in a more formal way, by giving definitions of the algorithms G, E, and D. You may use English to describe the algorithms, but use the form of an equation and use variables. DO describe the operations specific to this scheme. DO NOT write a particular key, ciphertext, or plaintext. Embrace variables.

I just need help with question #3 please, the other information is just there for reference.