17 и 18 ДАЮ 20 БАЛЛОВ!

1)

6 5/27 - (x - 1 2/9) = 3 20/81

x - 1 2/9 = 6 5/27 - 3 20/81

x - 1 2/9 = 6 15/81 - 3 20/81

x - 1 2/9 = 5 96/81 - 3 20/81

x - 1 2/9 = 2 76/81

x = 2 76/81 + 1 2/9

x = 2 76/81 + 1 18/81

x = 3 94/81

x = 4 13/81

Ответ: 4 13/81

2)

9 9/28 - (4 5/21 - x) = 6 2/7

4 5/21 - x = 9 9/28 - 6 2/7

4 5/21 - x = 9 9/28 - 6 8/28

4 5/21 - x = 3 1/28

x = 4 5/21 - 3 1/28

x = 4 140/588 - 3 21/588

x = 1 119/588

x = 1 17/84

Ответ: 1 17/84

3)

3 5/36 - (1 31/54 - x) = 1 17/27

1 31/54 - x = 3 5/36 - 1 17/27

1 31/54 - x = 339/108 - 176/108

1 31/54 - x = 163/108

1 31/54 - x = 1 55/108

x = 1 31/54 - 1 55/108

x = 1 62/108 - 1 55/108

x = 7/108

Ответ: 7/108

Ответ:

17. 1 17/84.

18. 7/108.

Объяснение:

17.

9 9/28 - (4 5/21 - x) = 6 2/7

9 9/28 - 4 5/21 + x = 6 2/7

х = 6 2/7 + 4 5/21 - 9 9/28

х = 6 24/84 + 4 20/84 - 9 27/84

х = 1 17/84

Ответ: 1 17/84.

18.

3 5/36 - (1 31/54 - х) = 1 17/27

3 5/36 - 1 31/54 + х = 1 17/27

3 15/108 - 1 62/108 + х = 1 68/108

х = 1 68/108 + 1 62/108 - 3 15/108

х = 3 22/108 - 3 15/108

х = 7/108

Ответ: 7/108.