Answer
For $(x_{1}, y_{1})$: $0$
For $(x_{2}, y_{2})$: $\approx2$
Work Step by Step
For $(x_{1}, y_{1})$: the slope is $0$ because the line is horizontal.
For $(x_{2}, y_{2})$: Since the question is just asking for an estimate, you can count the number of squares from two points and find the slope. For example: using points $(0,-4)$ and a point which can be approximated to $(2,0)$ you can use the $\frac{Δy}{Δx}$ formula:
$\frac{0- -4}{2-0} = \frac{4}{2} = 2$
