Quotient Group of Abelian Group is Abelian

Theorem
Let $G$ be an abelian group.

Let $N \le G$.

Then the quotient group $G / N$ is abelian.

Proof
First we note that because $G$ is abelian, from Subgroup of Abelian Group is Normal we have $N \triangleleft G$.

Thus $G / N$ exists for all subgroups of $G$.

Let $X = x N, Y = y N$ where $x, y \in G$.

From the definition of coset product:

Thus $G / N$ is abelian.