1.2 - 2 1/2 - 3 1/3 + 5.6 - (-2.1)

Convert all the mixed numbers to improper fractions:

1.2 = 1.2
2 1/2 = 5/2
3 1/3 = 10/3
5.6 = 28/5
-2.1 = -2.1

Now simplify the expression:

1.2 - 5/2 - 10/3 + 28/5 + 2.1

Using a common denominator of 30:

(1.2 30) - (5/2 15) - (10/3 10) + (28/5 6) + (2.1 * 30)

36 - 75 - 100 + 336 + 63

Now add all the terms together:

36 - 75 - 100 + 336 + 63 = 260

Therefore, 1.2 - 2 1/2 - 3 1/3 + 5.6 - (-2.1) = 260.