1. The problem statement, all variables and given/known data Suppose a, b ∈ N and a|b. Prove that a = gcd(a, b). 2. Relevant equations Seems easy intuitively but actually proving it is giving me problems. 3. The attempt at a solution I have been trying to use the fact that gcd(a,b)=na + mb here m and n are integeres but got stuck.