Final answer:
The equation y = 9 + 3x represents a line with a y-intercept of 9 and a slope of 3. To translate the line down 3 units, subtract 3 from every y-coordinate.
Step-by-step explanation:
The equation y = 9 + 3x represents a line with a y-intercept of 9 and a slope of 3. The y-intercept is the point where the line intersects the y-axis, and in this case, it is the point (0, 9). The slope of 3 means that for every increase of 1 on the horizontal axis, the line rises up 3 units on the vertical axis.
To translate the line down 3 units, we can subtract 3 from every y-coordinate. This means that the equation becomes y = 9 + 3x - 3, which simplifies to y = 6 + 3x.