The calculated distance (air line) between Roquebrune-sur-Argens and Marseille is approximately 64 miles respectively 103 kilometers.
By car or train, the actual journey to Marseille is certainly longer, as only the direct route (as the crow flies) between Roquebrune-sur-Argens and Marseille has been calculated here.
Air line (approximately)
103 kilometers
56 nautical miles