21,4 - 5 1/2 - (16 2/3 - 6,6)

First, let's solve the expression within the parentheses:

16 2/3 - 6,6 = 16 2/3 - 6.6 = 16 + 2/3 - 6.6 = 16 + 2/3 - 66/10 = 16 + 2/3 - 20/3 = 16 + 2/3 - 20/3 = 16 + (2 - 20)/3 = 16 - 18/3 = 16 - 6 = 10

Now, substitute that back into the original expression:

21,4 - 5 1/2 - 10

Now, let's simplify the expression further:

21.4 - 5 1/2 - 10 = 21.4 - 5.5 - 10 = 21.4 - 5.5 - 10 = 21.4 - 15.5 = 5.9

So, 21,4 - 5 1/2 - (16 2/3 - 6,6) is equal to 5.9.