a) $\frac{3}{4}$ - x = 1
⇔ x = $\frac{3}{4}$ - 1 = $\frac{-1}{4}$
b) x + 4 = $\frac{1}{5}$
⇔ x = 4 - $\frac{1}{5}$ = $\frac{19}{5}$
c) x - $\frac{1}{5}$ = 2
⇔ x = 2 + $\frac{1}{5}$ = $\frac{11}{5}$
d) x + $\frac{3}{5}$ = $\frac{1}{81}$
⇔ x = $\frac{1}{81}$ - $\frac{3}{5}$ = $\frac{-238}{405}$