Answer:
[tex](-\infty ,\infty)[/tex]
[tex]y\in \mathbb{R}[/tex]
Step-by-step explanation:
[tex]$y=3-\frac{x}{3} $[/tex]
The domain is all Real numbers.
The range is all Real numbers.
Once it is a linear an equation and there's no restriction for x, both domain and range will be all Real numbers.