Don't know exactly what year these are, but as far as some that I found for sale,they're not worth much.
Edit - Also,you're way off on the date.Since that guitar looks nothing like a 70s style Ibanez, I checked the Vintaxe Ibanez catalogs,figuring by its style it would have to be mid or late 80s or maybe 1990s.The RX series first appears in the 1994 catalog,pages 15-17.Also found out the RX 20 is the entry level model of the series and that the RX series guitars were made in both Korea and Indonesia.