a) -x-3/4=-8/11 <=> -$\frac{44x+33}{44}$ =-$\frac{32}{44}$
<=> 44x+33=32 <=> 44x=-1 <=> x=-$\frac{1}{44}$
b) $\frac{11}{12}$ - ($\frac{2}{5}$ +x)=$\frac{2}{3}$
<=> $\frac{55}{60}$ - $\frac{24}{60}$ - $\frac{60x}{60}$ = $\frac{40}{60}$
<=>- $\frac{3}{20}$ = $\frac{20x}{20}$ <=> 3=20x <=> x=$\frac{3}{20}$