You would use the point-slope equation of y-y₁=mx(x-x₁)
So the rate of change is the slope and equals m, so m=-4
and has a solution at (-5,2) which would be the (x₁, y₁) and then it is just plugging in the numbers
y - (2) = (-4)(x - (-5))
y - 2 = -4 (x+5)
y - 2 = -4x - 20
y = -4x - 18
