On a straight road, a car speeds up at a constant rate from rest to 20 m/s over a 5 second interval and a truck slows at a constant rate from 20 m/s to a complete stop over a 10 second interval. how does the distance traveled by the truck compare to that of the car?

To determine the total distance traveled by an object in constant speed, just multiply the speed by the time. So, for the car, the total distance traveled is,
                               distance by car = (20 m/s)(5s) = 100 m
For decelerating object, the distance traveled is,
                          distance = Vt - (at^2)/2
For the truck,
         distance by truck = (20 m/s)(10s) - (2m/s^2)((10s)^2)/2 = 100 m

Relatively, both have traveled the same distance. 

The answer to your question is b