Ответ:

Пошаговое объяснение:

1.

1) 2/7 + 3. 1/2 = 4/14 + 3. 7/14 = 3. 11/14

2) 3. 11/14 * 4. 2/3 = 53/14 * 14/3 = 53/3 = 17. 2/3

2.

1) 4. 1/5 - 2. 3/4 = 4. 4/20 - 2. 15/20 = 3. 24/20 - 2. 15/20 = 1. 9/20

2) 1. 9/20 * 2. 2/19 = 29/20 * 40/19 = 29/1 * 2/19 = 58/19 = 3. 1/19

3.

1) 5. 6/7 + 3. 5/21 = 5. 18/21 + 3. 5/21 = 8. 23/21 = 9. 2/21

2) 9. 2/21 * 2. 1/10 = 191/21 * 21/10 = 191/10 = 19. 1/10

4.

1) 7. 5/12 - 3. 1/6 = 7. 5/12 - 3. 2/12 = 4. 3/12 = 4. 1/4

2) 4. 1/4 * 2. 2/17 = 17/4 * 36/17 = 36/4 = 9