To solve the slope, use the equation:
slope = (y₂ - y₁)/(x₂ - x₁)
Let:
(x₁, y₁) = (18, 5) & (x₂, y₂) = (-8,-16)
Plug in corresponding numbers to the corresponding variables
(y₂ - y₁)/(x₂ - x₁) = (-16 - 5)/(-8 - 18)
Simplify
(-16 - 5)/(-8 - 18) = -21/-26
Simplify
-21/-26 = 21/26
21/26 is the slope
hope this helps