a)
ô 1 = $\frac{-1}{3}$ - $\frac{1}{3}$ = $\frac{-2}{3}$
ô 2 = $\frac{1}{3}$ - $\frac{-1}{3}$ = $\frac{2}{3}$
ô 3 = $\frac{-2}{3}$ - $\frac{2}{3}$ = $\frac{-4}{3}$
ô 4 = $\frac{-1}{3}$ - $\frac{1}{3}$ = $\frac{-2}{3}$
ô 5 = $\frac{2}{3}$ - $\frac{-2}{3}$ = $\frac{4}{3}$
ô 6 = $\frac{-4}{3}$ - $\frac{4}{3}$ = $\frac{-8}{3}$
b)
ô 6 = $\frac{-1}{4}$ / $\frac{-1}{2}$ = $\frac{1}{2}$
ô 4 = $\frac{1}{2}$ * $\frac{-1}{3}$ = $\frac{-1}{6}$
ô 2 = $\frac{-1}{4}$ * $\frac{-1}{6}$ = $\frac{1}{24}$
ô 1 = $\frac{-1}{6}$ / $\frac{1}{224}$ = -4
ô 3 = -4 / $\frac{-1}{4}$ = 16
ô 5 = 16 / $\frac{-1}{2}$ = -32