The calculated distance (air line) between Lenart v Slov. Goricah and Brežice is approximately 48 miles respectively 77 kilometers.
By car or train, the actual journey to Brežice is certainly longer, as only the direct route (as the crow flies) between Lenart v Slov. Goricah and Brežice has been calculated here.
Air line (approximately)
77 kilometers
42 nautical miles