The calculated distance (air line) between Saint-Germain-lès-Arpajon and Reims is approximately 92 miles respectively 149 kilometers.
By car or train, the actual journey to Reims is certainly longer, as only the direct route (as the crow flies) between Saint-Germain-lès-Arpajon and Reims has been calculated here.
Air line (approximately)
149 kilometers
80 nautical miles