Ответ:

Пошаговое объяснение:

1. 7/15 - 3/40 - 1/24 = (56-9-5) / 120 = 42/120 = 21/60

2. 21/60 :  0,7 = 21/60 : 7/10 = 21/60 * 10/7 = 1/2

3. 2,4 * 1/3 = 12/5 * 1/3 = 4/5

4. 4/5 - 3 = (4-15) / 5 = - 11/5

5. -11/5 * 5/11 = - 1

6. 1/2 : (-1) = - 1/2

7. 3/4 - 1 2/3 = 3/4 - 5/3 = -11/12

8. 1 5/6 : (-11/12) = 11/6 : (-11/12) = 11/6 * (-12/11) = - 2

9. 4/9 - 5/12 = 1/36

10. 1/36 + 0,75 = 1/36 + 3/4 = 28/36 = 7/9

11. 7/9 * 3/7 = 1/3

12. -2 : 1/3 = -2 * 3/1 = -6

13. - 1/2 * (-6) = 3