Ответ:

2 1/8 - (5 1/3 - x) =1 1/4

17/8 - (16/3 - x) =5/4

17/8 - 16/3 +x = 5/4

3*(17/8) - 8*(16/3)+x =5/4

(51-128)/24 +x = 5/4

-77/24 + x = 5/4

x = 5/4 + 77/24

x =8*(5/4) + 77/24

x = (40+77)/24

x = 107/24