Answer:
-2
Explanation:
Look at the bottom right point. To get to the point above it only moving vertical and horizontally, you would move 2 units up (or vertically) and one unit left (or horizontally).
The slope is negative. Imagine a person starting on the very left side of the line and he starts walking. As he walks on the line, he is going down hill. That tells us that the slope is negative.