a) $\frac{3}{4}$           und      $\frac{5}{7}$
_{=   und   =} also $\frac{3}{4}$ $\frac{5}{7}$

b) $\frac{3}{8}$             und     $\frac{5}{12}$
_{=   und   =} also $\frac{3}{8}$ $\frac{5}{12}$

c) $\frac{1}{6}$             und     $\frac{2}{15}$
_{=   und   =} also $\frac{1}{6}$ $\frac{2}{15}$

d) $\frac{9}{12}$             und     $\frac{11}{15}$
_{=   und   =} also $\frac{9}{12}$ $\frac{11}{15}$