1, $\frac{-8}{12}$ = $\frac{(-8):4}{12:4}$ = $\frac{-2}{3}$
2. $\frac{15}{-60}$ = $\frac{15:(-15)}{(-60):(-15)}$ = $\frac{-1}{4}$
3/ $\frac{-16}{72}$ = $\frac{-16:8}{72:8}$ = $\frac{-2}{9}$
4/ $\frac{35}{14.15}$ = $\frac{7.5}{2.7.3.5}$ = $\frac{1}{6}$