Congruence $320 \equiv 1 (\text{mod }x)$ I have the following congruence $320 \equiv 1 (\text{mod }x)$
And the question is : find all the modulos $x$ that make this congruence true.

Well basically the definition of $$a \equiv b (\text{mod }n)$$ is that n should divide $(a-b)$ So according to your question $x$ should divide $320-1$ that is $319$. It would be $11$ and $29$
Since you want all the $x$'s then it would be $11$, $29$ and $319$
