Two drivers travel on a 3% downgrade road with a speed limit of 60mi/h. Both drivers have a perception-reaction time of 2.5 seconds. If one of the two drivers is obeying the speed limit and the other driver is traveling illegally at 80mi/h, calculate the following: 

a) The distance each driver needs to perceive/react to the need to stop. 

b) The total stopping distance required for every driver.