Step-by-step explanation: To find the slope of a line with a negative slope, we would use the ratio rise/run between any two points that are on that line.
Let's look at an example which I have provided in the image attached. I have labeled two points which are points A and B.
Notice however that to get from point A to point B, we must first go down 3 units so we say that our rise is -3. From there we move 4 units to the right so our run is 4. So our slope or rise over run is -3/4.