The calculated distance (air line) between Rishon LeTsiyyon and Bet Shemesh is approximately 20 miles respectively 33 kilometers.
By car or train, the actual journey to Bet Shemesh is certainly longer, as only the direct route (as the crow flies) between Rishon LeTsiyyon and Bet Shemesh has been calculated here.
Air line (approximately)
33 kilometers
18 nautical miles