On a **motorway**, overtaking must always be done on the **left side** of the vehicle you wish to overtake. This is a general traffic rule that applies to motorways and similar roads.

There are some exceptions where overtaking on the right is allowed, but these do not apply to motorways. For example, you can overtake on the right in urban areas if there are at least two lanes in the same direction, or when a tram is running in the center of the road. However, these situations do not occur on motorways.

Additionally, on motorways, the lanes are designed to facilitate traffic flow and avoid dangerous maneuvers. Overtaking on the right could cause confusion and increase the risk of accidents, as drivers do not expect a vehicle to overtake them on that side.

Therefore, the correct answer is that **you cannot overtake on the right on a motorway**.