First thing to do is find out the coordinates of two points on the graph (I will use the ones that have been marked by the red dots):
Point A: (3, -1)
Point B: (1, 2)
Then we will use the slope formula to work out the slope:
y₂ - y₁ / x₂ - x₁
Substitute in our points:
2 - (-1) / 1 - 3
Then we work out the expression (remember a negative and a negative make a positive!):
3 / -2
Then we check if we can simplify this fraction, which in this case we cannot.
Therefore the slope of that line would be:
3 / -2
(remember to write it as a fraction!)