Приведите дроби к общему знаменателю и выполните действия:
а)
$\frac{1}{2} + \frac{1}{4}$;
$\frac{1}{2} + \frac{5}{7}$;
$\frac{1}{4} + \frac{5}{6}$;
б)
$\frac{5}{8} + \frac{5}{24}$;
$\frac{4}{5} + \frac{1}{6}$;
$\frac{3}{20} + \frac{7}{25}$;
в)
$\frac{1}{2} - \frac{1}{8}$;
$\frac{1}{2} - \frac{1}{3}$;
$\frac{5}{6} - \frac{3}{8}$;
г)
$\frac{3}{4} - \frac{1}{12}$;
$\frac{5}{7} - \frac{2}{3}$;
$\frac{9}{10} - \frac{3}{4}$.
$\frac{1}{2} + \frac{1}{4} = \frac{2}{4} + \frac{1}{4} = \frac{2 + 1}{4} = \frac{3}{4}$;
$\frac{1}{2} + \frac{5}{7} = \frac{7}{14} + \frac{10}{14} = \frac{7 + 10}{14} = \frac{17}{14}$;
$\frac{1}{4} + \frac{5}{6} = \frac{3}{12} + \frac{10}{12} = \frac{3 + 10}{12} = \frac{13}{12}$.
$\frac{5}{8} + \frac{5}{24} = \frac{15}{24} + \frac{5}{24} = \frac{15 + 5}{24} = \frac{20}{24} = \frac{5}{6}$;
$\frac{4}{5} + \frac{1}{6} = \frac{24}{30} + \frac{5}{30} = \frac{24 + 5}{30} = \frac{29}{30}$;
$\frac{3}{20} + \frac{7}{25} = \frac{15}{100} + \frac{28}{100} = \frac{15 + 28}{100} = \frac{43}{100}$.
$\frac{1}{2} - \frac{1}{8} = \frac{4}{8} - \frac{1}{8} = \frac{4 - 1}{8} = \frac{3}{8}$;
$\frac{1}{2} - \frac{1}{3} = \frac{3}{6} - \frac{2}{6} = \frac{3 - 2}{6} = \frac{1}{6}$;
$\frac{5}{6} - \frac{3}{8} = \frac{20}{24} - \frac{9}{24} = \frac{20 - 9}{24} = \frac{11}{24}$.
$\frac{3}{4} - \frac{1}{12} = \frac{9}{12} - \frac{1}{12} = \frac{9 - 1}{12} = \frac{8}{12} = \frac{2}{3}$;
$\frac{5}{7} - \frac{2}{3} = \frac{15}{21} - \frac{14}{21} = \frac{15 - 14}{21} = \frac{1}{21}$;
$\frac{9}{10} - \frac{3}{4} = \frac{18}{20} - \frac{15}{20} = \frac{18 - 15}{20} = \frac{3}{20}$.