$\frac{9}{18}=\frac{9:9}{18:9}=\frac{1}{2}$
$\frac{12}{24}=\frac{12:12}{24:12}=\frac{1}{2}$
$\frac{12}{16}=\frac{12:4}{16:4}=\frac{3}{4}$
$\frac{15}{20}=\frac{15:5}{20:5}=\frac{3}{4}$
Ответ:
$\frac{9}{18}=\frac{12}{24}=\frac{1}{2}$
$\frac{12}{16}=\frac{15}{20}=\frac{3}{4}$