20/29 - (x-12/29) = 5/29

20/29 - x + 12/29 = 5/29

(20 + 12)/29 - x = 5/29

32/29 - x = 5/29

-x = 5/29 - 32/29

-x = -27/29

x = 27/29

Ответ: x = 27/29.