Решебник по математике 5 класс Виленкин Часть 1, 2 Часть 2. Параграф 5. Обыкновенные дроби Задание 412

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\[\textbf{а)}\ \frac{7}{9} - \frac{5}{12} = \frac{28}{36} - \frac{15}{36} = \frac{13}{36}\ \]

\[\textbf{б)}\ \frac{11}{12} - \frac{11}{20} = \frac{55}{60} - \frac{33}{60} = \frac{22}{60} =\]

\[= \frac{11}{30}\ \]

\[\textbf{в)}\ \frac{5}{6} + \frac{7}{8} = \frac{20}{24} + \frac{21}{24} = \frac{41}{24} = 1\frac{17}{24}\ \]

\[\textbf{г)}\ \frac{17}{21} - \frac{8}{15} = \frac{85}{105} - \frac{56}{105} = \frac{29}{105}\ \]

\[\textbf{д)}\ 13\frac{21}{22} - 11\frac{3}{55} =\]

\[= 13\frac{105}{110} - 11\frac{6}{110} = 2\frac{99}{110} =\]

\[= 2\frac{9}{10}\ \]

\[\textbf{е)}\ 8\frac{5}{40} + 7\frac{10}{60} =\]

\[= 8\frac{15}{120} + 7\frac{20}{120} = 15\frac{35}{120} =\]

\[= 15\frac{7}{24}\text{\ \ }\]