Choose an example of a vertical motion with a negative velocity and a negative acceleration.

  A body falling down towards earth, when upward direction is considered as positive direction got negative velocity and acceleration.

Explanation:

     You are standing on top of a building with certain height, H and you select height of building to be positive. If you throw a stone upward it's displacement is increasing and velocity is decreasing, both of them are positive and it is attracted towards earth by an acceleration so it is downward. SO it's value is negative.

   After reaching the maximum height the stone comes down and it's velocity increases in the downward direction, in this situation it is having negative velocity and and negative acceleration.