Два целых 11/12 - (x +3/8) = 1,25

\[ 2\frac{11}{12}-\left(x+\frac38\right)=1{,}25 \]

\[ x=2\frac{11}{12}-1{,}25-\frac38 \]

\[ x=\frac{35}{12}-\frac54-\frac38=\frac{31}{24}=1\frac7{24} \]

Ответ: \(x=1\frac7{24}\)