Follow the formula:
(y₂ - y₁)/(x₂ - x₁)
Set (-3, -6) as (x₁, y₁)
Set (-6, 12) as (x₂, y₂)
Plug in the numbers to the corresponding places.
(12 - (-6))/(-6 -(-3))
(12 + 6)/(-6 +3) *remember that two negatives = a positive
Combine the terms
18/-3
divide.
18/-3 = -6
The slope of the line is -6/1
hope this helps