9.2/5 - (8.1/3-7.1/4+5.1/6);

9 2/5 - (8 1/3 - 7 1/4 + 5 1/6) = 2 9/10

8 1/3 - 7 1/4 = 25/3 - 28/4 = (100-84) / 12 = 16/12

16/12 + 5 1/6 = 16/12 + 31/6 = (16+62) / 12 = 78/12

9 2/5 - 78/12 = 47/5 - 78/12 = (564-390) / 60 = 174/60 = 2 54/60 = 2 27/30 = 2 9/10