Hello! So what we have to do is find the least common denominator for 3, 7, and 9, which is 63. 1/3 is 21/63, 2/7 is 18/63, and 2/9 is 14/63. The denominator stays the same. But add the numerators together. 21 + 18 + 14 is 53. Tara has read 53/63 of the book.