Complex sentence: In 1989, Air Malta exercised an option for one more A320, and in 1992,3 more Boeing 737--300 were ordered and 4 Avro RJ70 were ordered for routes to Catania and Palermo and to new destinations such as Tunis and Monastir.
Split into simpler sentences: In 1989, Air Malta exercised an option for one more A320, and in 1992, three more Boeing 737--300s were ordered. That year, four Avro RJ70s were ordered for routes to Catania and Palermo and to new destinations such as Tunis and Monastir.