You need to solve , that is, in . Do you know how to do this?
So... each letter from A to Z corresponds to a number 0 to 25. Now I want to find the pairs (x,y) such that in ,
And we are only told that for (A, A), which corresponds to (0,0), this holds.
So, how do I find all pairs x, y such that they are unchanged by the multipication? Going through all possible combinations of x and y is a real daunting task. Is there an easy way for finding all the pairs?
P.S. In ,