19 - 11 1/6 + 2 5/6 = 10 целых 2/3
1) 19 - 11 1/6 = 18 6/6 - 11 1/6 = 7 5/6
2) 7 5/6 + 2 5/6 = 9 10/6 = 10 4/6 = 10 2/3
