3. 6) (1,09-0,29) + 1 8/9 / (18,9-16 13/20)

1. Calculate the first term: (1.09 - 0.29) + 1 8/9 = 0.8 + 17/9 = 0.8 + 1.888... = 2.688...
2. Calculate the second term: (18.9 - 16 13/20) = 18.9 - 16.65 = 2.25.
3. Divide the first term by the second term: 2.688... / 2.25 = 1.195...