16 - 10,9 : ( 1 целая 1/18 - 3 целых 2/27)

16 - 10,9 : (1 1/18 - 3 2/27) = 21,4
1) 1 1/18 - 3 2/27 = 1 3/54 - 3 4/54 = - (3 4/54 - 1 3/54) = -2 1/54
2) 10,9 : (-2 1/54) = 109/10 : (-109/54) = 109/10 * (-54/109) = -27/5 = -5,4
3) 16-(-5,4)=16+5,4=21,4