Homework Statement
If a≡b(mod n) and d=gcd(a.n), prove that d=gcd(b,n).[/B]Homework Equations
If a≡b(mod n) → n|(a-b) → a-b =nk, for some k∈ℤ → a=nk+b
If d=gcd(a.n) → d=ax+ny
gcd(b,n)=d ↔ d|b and d|n, and if c|b and c|n, then c ≤ a.
The Attempt at a Solution
Since a=nk+b and d=ax+ny, then...