Answer:
-3
Step-by-step explanation:
Select a point on the red line that crosses the graph at a corner like point (2,2). Start at the middle of the graph and go 2 spaces to the right on the x axis and then 2 spaces up. Now you will be a the point (2,2). Do you see how the right line is hitting at the top left corner of the square?
From this point, count how many spaces up and how many spaces to the left to get to the next spot that the red line touches a corner. If you go up 3 spaces and left 1, you have found the next corner. The slope is -3/1 or -3.
The slope is negative because the x and y's are going in different directions, as the x is getting bigger, the why is getting smaller, or another way of looking at it, is that I went up to the find slope and up is positive, but then I went left 1 and left is toward the negative numbers. A positive divided by a negative is a negative, so the slope is negative.