1)4/27 : x + 5/6 = 8/9 2)6/21 : (8 1/6

1) 4/27 : x + 5/6 = 8/9;

4/27 : x = 8/9 - 5/6;

4/27 : x = (8 * 2 - 5 * 3)/18;

4/27 : x = (16 - 15)/18;

4/27 : x = - 1/18;

4/27 * 1/x = - 1/18;

4/27x= - 1/18;

- 27x = 4 * 18;

- 27x = 72;

x = 72 : (- 27);

x = - 2 18/27;

x = - 2 2/3.

Ответ: - 2 2/3.

2) 6/21 : (8 1/6 - x) = 3/77;

6/21 : (49/6 - х) = 3/77;

3/77 * (49/6 - x) = 6/21;

49/6 - x = 6/21 : 3/77;

49/6 - x = 6/21 * 77/3;

49/6 - x = (2 * 77)/21;

49/6 - x = 154/21;

- x = 154/21 - 49/6;

- x = (154 * 2 - 49 * 7)/6;

- x = (308 - 343)/6;

- x = - 35/6;

x = 35/6;

x = 5 5/6.

Ответ: 5 5/6.

3) 81/121 * 1 1/54 + 26/55 : 1 4/35 = 81/121 * 55/54 + 26/55 * 35/39 = (27 * 55)/(121 * 18) + (26 * 7)/(11 * 39) = (3 * 55)/(121 * 2) + 182/429 = 165/242 + 182/429 = (165 * 429 + 182 * 242)/(242 * 429) = (70785 + 44044)/103818 =114829/103818 = 1 11011/103818 = 1 1001/9438.