A generalization of the Caesar cipher, known as the affine Caesar cipher, has the following form: For each plaintext letter p, substitute the cipher text letter

C: C = E([a, b], p) = (ap + b) mod 26

A cipher text has been generated with an affine cipher. The most frequent letter of

the cipher text is B, and the second most frequent letter of the cipher text is U.

Break this code by solving a and b. (Assume that the most frequent plaintext letter is e and the second most frequent letter is t.)