Question Number 125890 by geraldinebalasta last updated on 15/Dec/20
$$\left(\mathbb{Z}^{+,\ast} \right)\:{where}\:{x}^{\ast} {y}=\:{x}−{y}\:{for}\:{all}\:{x},{y}\:\in\:{z}^{+} . \\ $$
Commented by talminator2856791 last updated on 15/Dec/20
$$\:\mathrm{what}\:\mathrm{is}\:\mathrm{the}\:\mathrm{question}? \\ $$