12-4 целых 3/4, 11-5 целых 3/13, 2 целых 3/4-1 целая 7/12, 18-3 целых 7/13, 10 целых 1/2-4 целых 5/14. (х-4,7) * 7,3=38,69

12 - 4 3/4 = 12 - 19/4 = (12 * 4 - 19 * 1) / 4 = (48 - 19) / 4 = 29/4 = 7 1/4;

11 - 5 3/13 = 11 - 68/13 = (11 * 13 - 68 * 1) / 13 = (143 - 68) / 13 = 75/13 = 5 10/13;

2 3/4 - 1 7/12 = 11/4 - 19/12 = (11 * 3 - 19 * 1) / 12 = (33 - 19) / 12 = 14/12 = 7/6 = 1 1/6;

18 - 3 7/13 = 18 - 46/13 = (18 * 13 - 46 * 1) / 13 = (234 - 46) / 13 = 188/13 = 14 6/13;

10 1/2 - 4 5/14 = 21/2 - 61/14 = (21 * 7 - 61 * 1) / 14 = (147 - 61) / 14 = 86/14 = 43/7 = 6 1/7.

(х - 4,7) * 7,3 = 38,69;

х - 4,7 = 38,69 : 7,3;

х - 4,7 = 5,3;

х = 5,3 + 4,7;

х = 10.

Ответ: 10.