Final answer:
The equation can be rewritten as y + 3x = 6 (D).
Step-by-step explanation:
The given equation is y = 6 - 3x.
To rewrite this equation, we need to rearrange the terms. Add 3x to both sides of the equation to isolate the y term: y + 3x = 6.
Therefore, the correct rewrite of the equation is y + 3x = 6, or option D.