First, let's simplify the fractions:

11/12 - 9/10 = (1110 - 912) / (12*10)
= (110 - 108) / 120
= 2 / 120
= 1 / 60

Now let's simplify the expression further:

(1/60) (3 - 4/3) = (1/60) (9/3 - 4/3)
= (1/60) (5/3)
= 5 / (60 3)
= 5 / 180
= 1 / 36

Therefore, 12•(11/12-9/10)•(3-1 1/3) = 1 / 36.