Problem $2$: Theoretical Stopping Distance

What distance will a vehicle travel before coming to a complete stop from a speed of $70$ mph if the coefficient of braking friction is $0\mathrm{.}28,$ and

$($a$)$ When the vehicle is traveling on a level roadway with no grade

$($b$)$ When the vehicle is traveling uphill on a roadway of constant grade $=0\mathrm{.}10$

$($c$)$ When the vehicle is traveling downhill on a roadway of constant grade $=0\mathrm{.}10$

Additionally answer: If the roadway grade is not constant but starts at $0\mathrm{.}10$ uphill and decreases to $0$ at a continuous rate, would the braking distance be equal to$,$ greater than, or less than that in the case of a constant $0\mathrm{.}10$ uphill grade,