The slope of a line is [tex]\frac{dy}{dx}[/tex]
where [tex]d[/tex] is the difference and [tex]y[/tex] and [tex]x[/tex] are the values.
In this case, the difference in [tex]y[/tex] is 10 and the difference in [tex]x[/tex] is 0
And division where the denominator being 0 leads to the answer being Undefined or Infinity as the line is directly on the [tex]y[/tex] axis.
