9514 1404 393
Answer:
positive
Explanation:
When considering the slope of a line, we usually choose "rise" and "run" so that "run" is positive, and "rise" measures the vertical change as one moves from left to right.
If we assume that "downhill" lines refers to lines that go from upper left to lower right (downhill to the right), then the rise is negative while the run is positive.
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Additional comment
Here, we assume a line is considered to be "downhill" if it has negative slope. In the real world, "downhill" is the direction the ball rolls under the influence of gravity. That direction might be behind you, or to your left, instead of in front of you or to the right.
Definitions are important in math. "Downhill" is not a term that is widely used to describe lines, so we have to guess the intended meaning here.