I will assume that we are trying to find the slope between (-9,2) and (9, 2)
The slope's equation ⇒ [tex]\frac{y2-y1}{x2-x1}[/tex]
Let's set the variables:
(x1, y1) --> (-9, 2)
(x2, y2) --> (9, 2)
Now let's plug them in:
[tex]Slope = \frac{2-2}{9--9} =\frac{0}{18} =0[/tex]
Thus the slope of the line is 0.
Hope that helps!