use the simple substitution cipher with key C=P+5 (mod 26) to encrypt the message " Be extra careful of boko haram"?

To encrypt the message "Be extra careful of boko haram" using the simple substitution cipher with key C=P+5 (mod 26), we need to substitute each letter with the corresponding letter that is 5 positions ahead in the alphabet.

Here is the encryption process:

Original message: Be extra careful of boko haram
Encrypted message: Gj jwfyf hfujsqj tk gtpt mfwfr

Explanation:
- B (letter at position 2) is substituted with G (letter at position 7).
- E (letter at position 5) is substituted with J (letter at position 10).
- Space remains unchanged.
- C (letter at position 3) is substituted with H (letter at position 8).
- A (letter at position 1) is substituted with F (letter at position 6).
- R (letter at position 18) is substituted with W (letter at position 23).
- E (letter at position 5) is substituted with J (letter at position 10).
- X (letter at position 24) is substituted with C (letter at position 3).
- T (letter at position 20) is substituted with Y (letter at position 25).
- R (letter at position 18) is substituted with W (letter at position 23).
- A (letter at position 1) is substituted with F (letter at position 6).
- Space remains unchanged.
- C (letter at position 3) is substituted with H (letter at position 8).
- A (letter at position 1) is substituted with F (letter at position 6).
- R (letter at position 18) is substituted with W (letter at position 23).
- E (letter at position 5) is substituted with J (letter at position 10).
- F (letter at position 6) is substituted with K (letter at position 11).
- U (letter at position 21) is substituted with Z (letter at position 26).
- L (letter at position 12) is substituted with Q (letter at position 17).
- Space remains unchanged.
- O (letter at position 15) is substituted with T (letter at position 20).
- F (letter at position 6) is substituted with K (letter at position 11).
- Space remains unchanged.
- B (letter at position 2) is substituted with G (letter at position 7).
- O (letter at position 15) is substituted with T (letter at position 20).
- K (letter at position 11) is substituted with P (letter at position 16).
- O (letter at position 15) is substituted with T (letter at position 20).
- Space remains unchanged.
- H (letter at position 8) is substituted with M (letter at position 13).
- A (letter at position 1) is substituted with F (letter at position 6).
- R (letter at position 18) is substituted with W (letter at position 23).
- A (letter at position 1) is substituted with F (letter at position 6).
- M (letter at position 13) is substituted with R (letter at position 18).

Therefore, the encrypted message is "Gj jwfyf hfujsqj tk gtpt mfwfr".