Question

How do you find the slope of a line `y=5`?

Answer 1

You could re-write the given equation `y=5` in slope-intercept form as
`color(white)("XXXXX")` `y = 0*x +5` with a slope of `0` and a y-intercept of `5`.

or you could simply recognize this equation as a horizontal line with slope of `0`