Question

How do you find the slope of the line `y=-4`?

Answer 1

Slope`=0`

Explanation:

This is a perfectly horizontal line neither going up (slope positive) nor down (slope negetive).
Graphically:
graph{0x-4 [-10, 10, -5, 5]}
The slope is given numerically by the ratio:
`(Deltay)/(Deltax)` but `y=-4` always;
so `Deltay=0` always!