Решебник по математике 5 класс Виленкин Часть 1, 2 Часть 2. Параграф 5. Обыкновенные дроби Задание 380

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\[\textbf{а)}\ \frac{25}{45} = \frac{z}{9}\]

\[\frac{5}{9} = \frac{z}{9}\]

\[z = 5\text{.\ }\]

\[Ответ:z = 5.\ \]

\[\textbf{б)}\ \frac{z}{7} = \frac{36}{42}\]

\[\frac{z}{7} = \frac{6}{7}\]

\[z = 6\text{.\ }\]

\[Ответ:z = 6.\ \]

\[\textbf{в)}\ \frac{39}{78} = \frac{3}{z}\ \]

\[\frac{3}{6} = \frac{3}{z}\]

\[z = 6\text{.\ }\]

\[Ответ:z = 6\text{.\ }\]

\[\textbf{г)}\ \frac{7}{z} = \frac{35}{40}\]

\[\frac{7}{z} = \frac{7}{8}\]

\[z = 8\text{.\ }\]

\[Ответ:z = 8\text{.\ \ }\]