To solve this expression, we need to simplify each fraction and then perform the addition.

Starting with the first fraction, -2/7, there is no simplification that can be done.

Moving on to the second fraction, 1/3, it is already in its simplest form.

For the third fraction, -9/(-7), we can simplify it by dividing both the numerator and denominator by -1, resulting in 9/7.

Now we can add the fractions:

-2/7 + 1/3 + 9/7

To add fractions, we need to find a common denominator. In this case, the common denominator is 21.

Converting each fraction to have a denominator of 21:

(-2/7) * (3/3) = -6/21
(1/3) * (7/7) = 7/21
(9/7) * (3/3) = 27/21

Now we can add the fractions:

-6/21 + 7/21 + 27/21

Adding the numerators:

(-6 + 7 + 27)/21

Simplifying the numerator:

28/21

The fraction 28/21 can be simplified by dividing both the numerator and denominator by 7:

(28/7) / (21/7) = 4/3

Therefore, the simplified expression is 4/3.