You are given two affine ciphers for which encryption is described by this pair of formulae: $y=5x+12$

$(mod26)y=11x+23(mod26)$

Write down the equivalent single encryption formula when encrypting with the first formula and then

the second formula. It will be in the form $y=x+(mod26)$ where $0,25.$

Show that each of the ciphertexts ZOMCIH and $ZKNGZR,$ which were obtained by shift

ciphers from one$-$word plaintexts, has two different decryptions.

e $4.$ The ciphertext $JLH$ was obtained by affine encryption with the function $9x+1$mod$26.$ Find

the plaintext.