To solve this expression, first simplify the mixed numbers within the parentheses:

2 - 1 = 1
9/11 - 9/11 = 0

So, the expression becomes:

2 - 1 9/11 = 1 2/11

Now, divide 1 2/11 by 8/21:

(1 2/11) / (8/21)

To divide by a fraction, multiply by its reciprocal:

(11/11 + 2/11) * (21/8)

(13/11) * (21/8)

Now, multiply straight across:

13 21 = 273
11 8 = 88

So, the simplified answer is 273/88 or approximately 3.11.