А) 5 целых 11/12 - 2 целых 1/6 - 1 целая 3/4 = 2
1) 5 11/12 - 2 1/6 = 5 11/12 - 2 2/12 = 3 9/12 = 3 3/4
2) 3 3/4 - 1 3/4 = 2
б) (15 - 4 целых 3/20) - (12 - 3 целых 8/15) = 2 целых 23/60
1) 15 - 4 3/20 = 14 20/20 - 4 3/20 = 10 целых 17/20
2) 12 - 3 8/15 = 11 15/15 - 3 8/15 = 8 целых 7/15
3) 10 17/20 - 8 7/15 = 10 51/60 - 8 28/60 = 2 целых 23/60