1. Speed, since we know that
, where s is speed, d is distance and t is time
2. Velocity, for velocity you need to consider the direction and displacement gives the direction of travel.
3. 25 mph, because

4. 50 mph east, velocity unlike speed has direction.
5.Velocity, displacement gives the formula
direction.
6. 0, the displacement is zero so velocity is zero
7. It decreases, speed is inversely proportional to time