Ответ:

4 8/9

Пошаговое объяснение:

1) 3/4 - 7/12 = 9/12 - 7/12 = 2/12 = 1/6

2) 3/5 - 3/10 = 6/10 - 3/10 = 3/10

3) 1/6 : 3/10 = 1/6 * 10/3 = 5/9

4) 9/10 - 7/8 = 36/40 - 35/40 = 1/40

5) 7/8 - 5/6 = 21/24 - 20/24 = 1/24

6) 1/40 : 1/24 = 1/40 * 24/1 = 3/5

7) 2 + 2 2/5 = 4 2/5 = 22/5

8) 3/4 + 3/7 = 21/28 + 12/28 = 33/28

9) 22/5 : 33/28 = 22/5 * 28/33 = 56/15

10) 5/9 + 3/5 = 25/45 + 27/45 = 52/45

11) 52/45 + 56/15 = 52/45 + 168/45 = 220/45 = 4 40/45 = 4 8/9