Answer:
-4
Step-by-step explanation:
Take any 4 points,
(-7,21) & (-4,9) as (x₁, y₁)/(x₂, y₂)
Slope(m) = (y₂-y₁)/(x₂-x₁)
(9-21)/(-4-(-7))
-12/(-4+7)
-12/3
