Method to solve A = mod( Bn, C) How would I go by solving an equation of the general form. 

A = mod ( Bn, C )

Solve for n knowing A, B and C
Where B and C are Natural numbers and A and n are whole numbers. Also the greatest common denominator between B and C is 1. 

If $A \not \in [0, C-1]$ then clearly there is no solution. Otherwise, we have
$$A \equiv Bn \pmod C.$$
Since $(B,C) = 1$, the inverse $B^{-1}$ exists modulo $C$, and we can multiply it on both sides to get:
$$AB^{-1} \equiv n \pmod C.$$
So your problem is simply to find the inverse $B^{-1}$, which can be done using the extended Euclidean algorithm.
