( x -4 11/28 ) + 5 13/28 =11 5/12 - 4 6/7

Решим пример по действиям:

1) 4 11/28 = (4 * 28 + 11)/28 = (112 + 11)/28 = 123/28;

2) 5 13/28 = (5 * 28 + 13)/28 = (140 + 13)/28 = 153/28;

3) 153/28 - 123/28 = (153 - 123)/28 = 30/28;

4) 11 5/12 = (11 * 12 + 5)/12 = (132 + 5)/12 = 137/12;

5) 4 6/7 = (4 * 7 + 6)/7= 34/7;

6) х = 137/12 - 34/7 - 30/28 = 137/12 - 68/14 - 15/14 = 137/12 - (68 + 15)/14 = 137/12 - 83/14 = 1918/168 - 996/168 = (1918 - 996)/168 = 922/168 = 461/84.

Ответ: х = 461/84.