Commutative B-Algebra Implies (zy)(zx)=xy

Theorem
Let $\left({B, \circ}\right)$ be a commutative $B$-algebra.

Then:
 * $\forall x, y, z \in X: \left ({z \circ y} \right) \circ \left ({z \circ x} \right)= x \circ y$

Proof
Let $x, y, z \in X$.

Then: