Answer
If the grade $\theta$ is negative then a greater distance is required to slow down. If the grade $\theta$ is positive, then a lesser distance is needed.
Work Step by Step
Comparing the data from Exercises 85 and 86, we get that with the negative grade $\theta=-2^{\circ}$ the braking distance was $194ft$. Meanwhile with the positive grade $\theta=3.5^{\circ}$ the braking distance was of $155ft$.
Since $194>155$ then the breaking distance for slowing down must be greater with negative grade values.
