1) 1/2 - 3/8 =

Для вычитания дробей нужно привести их к общему знаменателю. Вот решения: Столбец 1: 1) $\frac{1}{2} - \frac{3}{8} = \frac{4}{8} - \frac{3}{8} = \frac{1}{8}$ 2) $\frac{3}{7} - \frac{5}{14} = \frac{6}{14} - \frac{5}{14} = \frac{1}{14}$ 3) $\frac{3}{5} - \frac{4}{15} = \frac{9}{15} - \frac{4}{15} = \frac{5}{15} = \frac{1}{3}$ 4) $\frac{5}{8} - \frac{3}{16} = \frac{10}{16} - \frac{3}{16} = \frac{7}{16}$ 5) $\frac{2}{9} - \frac{1}{18} = \frac{4}{18} - \frac{1}{18} = \frac{3}{18} = \frac{1}{6}$ 6) $\frac{8}{13} - \frac{1}{26} = \frac{16}{26} - \frac{1}{26} = \frac{15}{26}$ 7) $\frac{7}{15} - \frac{7}{30} = \frac{14}{30} - \frac{7}{30} = \frac{7}{30}$ 8) $\frac{2}{19} - \frac{1}{38} = \frac{4}{38} - \frac{1}{38} = \frac{3}{38}$ 9) $\frac{5}{7} - \frac{3}{14} = \frac{10}{14} - \frac{3}{14} = \frac{7}{14} = \frac{1}{2}$ 10) $\frac{4}{21} - \frac{1}{7} = \frac{4}{21} - \frac{3}{21} = \frac{1}{21}$ Столбец 2: 1) $\frac{7}{20} - \frac{11}{50} = \frac{35}{100} - \frac{22}{100} = \frac{13}{100}$ 2) $\frac{17}{33} - \frac{5}{22} = \frac{34}{66} - \frac{15}{66} = \frac{19}{66}$ 3) $\frac{9}{20} - \frac{5}{8} = \frac{18}{40} - \frac{25}{40} = -\frac{7}{40}$ 4) $\frac{4}{7} - \frac{13}{28} = \frac{16}{28} - \frac{13}{28} = \frac{3}{28}$ 5) $\frac{5}{13} - \frac{14}{39} = \frac{15}{39} - \frac{14}{39} = \frac{1}{39}$ 6) $\frac{5}{8} - \frac{2}{7} = \frac{35}{56} - \frac{16}{56} = \frac{19}{56}$ 7) $\frac{3}{4} - \frac{5}{12} = \frac{9}{12} - \frac{5}{12} = \frac{4}{12} = \frac{1}{3}$ 8) $\frac{15}{23} - \frac{27}{46} = \frac{30}{46} - \frac{27}{46} = \frac{3}{46}$ 9) $\frac{9}{25} - \frac{14}{117} = \frac{1053}{2925} - \frac{350}{2925} = \frac{703}{2925}$ 10) $\frac{17}{35} - \frac{13}{28} = \frac{68}{140} - \frac{65}{140} = \frac{3}{140}$