The calculated distance (air line) between Mazyr and Davyd-Haradok is approximately 86 miles respectively 139 kilometers.
By car or train, the actual journey to Davyd-Haradok is certainly longer, as only the direct route (as the crow flies) between Mazyr and Davyd-Haradok has been calculated here.
Air line (approximately)
139 kilometers
75 nautical miles