a) [tex]\frac{18\div6}{12\div6}=\boxed{\frac{3}{2}=1\frac{1}{2}=1{,}5}[/tex]
b) [tex]\frac{32\div8}{24\div8}=\boxed{\frac{4}{3}=1\frac{1}{3}}[/tex]
c) [tex]\frac{48\div6}{42\div6}=\boxed{\frac{8}{7}=1\frac{1}{7}}[/tex]
d) [tex]-\frac{75\div25}{100\div25}=\boxed{-\frac{3}{4}}[/tex]
e) [tex]-\frac{144\div18}{90\div18}=\boxed{-\frac{8}{5}=-1\frac{3}{5}=-1{,}6}[/tex]
