Answer:the number of books that Sally sold is 21
Explanation:
Jack sold 126 books. Joe sold 1/2 as many books as many books as jack. This means that the number of books that Joe sold would be
1/2 × 126 = 63
Sally sold 1/3 as many books as joe. This means that the number of books that Sally sold would be
1/3 × 63 = 21 books.