1)7 - 3 2/9 2)9 11/12-7 5/8 3)11 3/14-5 5/6 4)(1 5/8- 2/5)+2 3/20 отдельные цифры это целое .

1)7 - 3 2/9 = 6 9/9 - 3 2/9 = 3 7/9
2)9 11/12-7 5/8 = 9 22/24 - 7 15/24 = 2 7/24
3)11 3/14-5 5/6 = 11 9/42 - 5 35/42 = 10 51/42 - 5 35/42 = 5 16/42 = 5 8/21
4)(1 5/8- 2/5)+2 3/20 = (1 25/40 - 16/40) + 2 3/20 = 1 9/40 + 2 3/20 = 1 9/40 + 2 6/40 = 3 15/40 = 3 3/8