$---$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 $025.$

$1)$ You encrypt messages using the affine function $9x+2$mod$26.$ Decrypt the ciphertext $GM.$

$2)$ You try to encrypt messages using the affine cipher $4x+1$mod$26.$ Find two letters that

encrypt to the same ciphertext letter.