Hi ! The answer would be 3/4.
To get this answer, the red line represents the RISE, and the blue line represents the RUN.
Your slope will always have RISE/RUN.
Now, you count how many squares there are in your rise, in this case, 3.
Then, you do the same for your run, which would be 4.
Rise/Run becomes 3/4.
What would determine it to be a negative? Well, if you see charts like these: You'll see that the red is going up, it is a positive slope, while the blue, which is going down, is a negative slope.
For example, if sales at your store increased, your slope would go up (positive), while if the opposite it'd go down (negative).
In this case, it is a positive slope.