( х - 1/4 ) : 1/3 = 5/6

(х - 1/4) : 1/3 = 5/6
х - 1/4 = 5/6 * 1/3
х - 1/4 = 5/18
х = 5/18 + 1/4
х = 10/36 + 9/36 
х = 19/36
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Проверка:
(19/36 - 1/4) : 1/3 = 5/6
(19/36 - 9/36) : 1/3 = 5/6 
10/36 * 3/1 = 5/6
30/36 = 5/6 
5/6 = 5/6

(x - 1/4) : 1/3 = 5/6
(x - 1/4) * 3 = 5"6
3x - 3/4 = 5/6
3x = 5/6 + 3/4
3x = 19/12
x = 19/36