<prompt> Rejea kifungu hapa chini na kisha jibu swali baadaye kwa lugha ile ile kama kifungu: Passage: Notes dually denominated in piastres and đồng were issued in 1953 for the State of Vietnam, which evolved into South Vietnam in 1954. On September 22, 1975, after the fall of Saigon, the currency in South Vietnam was changed to a liberation đồng worth 500 old Southern đồng. Swali: Nini ilikuwa mabadiliko baada ya kuanguka kwa baadhi ya miji katika Vietnam?  <response>: sarafu katika Vietnam Kusini 