The calculated distance (air line) between Ryazan’ and Severo-Zadonsk is approximately 66 miles respectively 106 kilometers.
By car or train, the actual journey to Severo-Zadonsk is certainly longer, as only the direct route (as the crow flies) between Ryazan’ and Severo-Zadonsk has been calculated here.
Air line (approximately)
106 kilometers
57 nautical miles