Question: Who sang background on the song En karusell when they were just 27 years old?
Sentence (from "Anni-Frid Lyngstad"): Anni-Frid Synni, Princess Reuss of Plauen (German: "Anni-Frid Synni, Prinzessin Reuß von Plauen" ; born Anni-Frid Synni Lyngstad, 15 November 1945), commonly known as Frida Lyngstad, or just by the mononym, Frida, is a Norwegian-born Swedish singer, songwriter, and environmentalist.
Relevant evidence: Yes