To describe the position of the train with respect to your position while considering that you are 10 m east of the train, you would choose the following options:
- –10 m (this indicates that the train is 10 m to the west of your position)
- 10 m west (this explicitly states the direction of the train relative to your position)
The other options, +10 m and 10 m east, do not accurately describe the train's position relative to you.