Question: Sedaka's Back is a compilation album that included songs that were turned into hits by other artists such as "Solitaire" by an American vocal and instrumental duo that recorded how many albums?   
Sentence (from "The Carpenters"): Producing a distinctively soft musical style, which combined Karen's contralto vocals with Richard's arranging and composition skills, they became one of the best-selling music artists of all time.
Relevant evidence: No