a, $\frac{1}{5}$ - x= $\frac{5}{6}$- $\frac{1}{4}$
⇔$\frac{1}{5}$ - x= $\frac{7}{12}$
⇔ x = $\frac{1}{5}$ - $\frac{7}{12}$
⇔ x = $\frac{-23}{60}$
Vậy x = $\frac{-23}{60}$
b, $\frac{1}{10}$ - (x-$\frac{3}{25}$)=$\frac{1}{5}$
⇔x-$\frac{3}{25}$ =$\frac{1}{10}$ - $\frac{1}{5}$
⇔x-$\frac{3}{25}$ =$\frac{2}{25}$
⇔ x= $\frac{2}{25}$ +$\frac{3}{25}$
⇔ x =$\frac{1}{5}$
Vậy x =$\frac{1}{5}$
