a. $\frac{-3}{10}$ - 0,125 + $\frac{-7}{10}$ + 1,125 = $\left ( \frac{-3}{10} + \frac{-7}{10} \right ) + (1,125 - 0,125)$ = -1 + 1 = 0
b. $\frac{-8}{3}$ . $\frac{2}{11}$ - $\frac{8}{3}$ : $\frac{11}{9}$ = $\frac{8}{3} . \frac{-2}{11} - \frac{8}{3} . \frac{9}{11}$ = $\frac{8}{3}. \left ( \frac{-2}{11} - \frac{9}{11} \right )$ = $\frac{8}{3} . (-1) = \frac{-8}{3}$