Hi all,

This question uses Standard Numbering: The letters a-z are numbered 0-25.

In ciphertext encrypted with a simple affine cipher, we have a crib: VJAFRA
is thought to encrypt SOLIEL.

How do i find the key K = ( a,b )?

I guess i know (18a+b)mod26 = 21 and (14a+b)mod26=9 and so on but im stuck. I have some memory of needing to find the multiplicative inverse of something somewhere also?