To compare these fractions, we need to find a common denominator. The least common multiple of 9 and 15 is 45.

Converting 7/9 to have a denominator of 45:
(7/9) * (5/5) = 35/45

Converting 13/15 to have a denominator of 45:
(13/15) * (3/3) = 39/45

Therefore, 7/9 is equivalent to 35/45 and 13/15 is equivalent to 39/45.

Now we can compare the fractions:
35/45 < 39/45

So, 7/9 is less than 13/15.