Zaprezentowane obliczenia są pomocnicze, często wystarczy wykonać je w głowie:) 

$\frac{4}{8}=\frac{4:4}{8:4}=\frac{1}{2}$

$3:6=\frac{3}{6}=\frac{3:3}{6:3}=\frac{1}{2}$

$\frac{18}{36}=\frac{18:9}{36:9}=\frac{2}{4}=\frac{2:2}{4:2}=\frac{1}{2}$

$\frac{21}{42}=\frac{21:21}{42:21}=\frac{1}{2}$

$15:30=\frac{15}{30}=\frac{15:15}{30:15}=\frac{1}{2}$

$36:72=\frac{36}{72}=\frac{36:9}{72:9}=\frac{4}{8}=\frac{4:4}{8:4}=\frac{1}{2}$

$3\frac{11}{22}=3\frac{11:11}{22:11}=3\frac{1}{2}=\frac{3\cdot 2+1}{2}=\frac{7}{2}$

$14:4=\frac{14}{4}=\frac{14:2}{4:2}=\frac{7}{2}$

$\frac{21}{6}=\frac{21:3}{6:3}=\frac{7}{2}$

$3\frac{7}{14}=3\frac{7:7}{14:7}=3\frac{1}{2}=\frac{7}{2}$

$\frac{49}{14}=\frac{49:7}{14:7}=\frac{7}{2}$

$\frac{28}{8}=\frac{28:4}{8:4}=\frac{7}{2}$

$3:4=\frac{3}{4}$

$\frac{12}{16}=\frac{12:4}{16:4}=\frac{3}{4}$

$\frac{21}{28}=\frac{21:7}{28:7}=\frac{3}{4}$

$6:8=\frac{6}{8}=\frac{6:2}{8:2}=\frac{3}{4}$

$75:100=\frac{75}{100}=\frac{75:25}{100:25}=\frac{3}{4}$

$\frac{33}{44}=\frac{33:11}{44:11}=\frac{3}{4}$

$\frac{33}{9}=\frac{33:3}{9:3}=\frac{11}{3}=3\frac{2}{3}$

$44:12=\frac{44}{12}=\frac{44:4}{12:4}=\frac{11}{3}=3\frac{2}{3}$

$3\frac{10}{15}=3\frac{10:5}{15:5}=3\frac{2}{3}$

$\frac{22}{6}=\frac{22:2}{6:2}=\frac{11}{3}=3\frac{2}{3}$

$66:18=\frac{66}{18}=\frac{66:6}{18:6}=\frac{11}{3}=3\frac{2}{3}$