Answer:
All real numbers
Step-by-step explanation:
If there are no holes in your graph (like a graphed point with an open circle) and your graph or equation is a line, the domain is all real numbers.
The domain is all the x's on a graph, where the graph exists, and any x that may go into the equation. Literally any x can go into a linear equation. Your graphed line goes forever in both directions, so the domain is all real numbers. (Only a vertical line would be a different answer)