Question

Find the inverse of the encrypting function

F(x) =(5-x) mod 26 , 0<=x<=25

And use it to decrypt the massage '' ZRQUBFNB''

Answer 1

The inverse function is the same

$F(x) =(5-x)\\ x=5-F(x)$

$x=(5-25)mod26=6=G\\ x=(5-17)mod26=14=O\\ x=(5-16)mod26=15=P\\ x=(5-20)mod26=11=L\\ x=(5-1)mod26=4=E\\ x=(5-5)mod26=0=A\\ x=(5-13)mod26=18=S\\ x=(5-1)mod26=4=E\\$

Answer: Go please