Answer:
The left graph is a positive slope (yellow box)
The middle graph has no slope (green)
The right graph has a negative slope (purple)
Step-by-step explanation:
The left graph has a positive slope because the slope increases left to right. We can see this because the line starts at the origin at zero (0, 0), and increases.
The right graph has a negative slope because the slope decreases left to right. We can see this because it starts a value greater than zero, and gradually decrease to zero.
The middle graph contains no slope because it is a straight horizontal line. If we were to calculate the slope, (rise/run) of two points, the slope is the same in every point. It is constant.