Решите уравнение:
1)

\frac{1}{3} x + \frac{1}{5} x + \frac{1}{6} x = \frac{21}{40}

;
2)

\frac{1}{4} x + \frac{1}{6} x + \frac{1}{8} x = \frac{39}{56}

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Математика 6 класс Мерзляк. Номер №764

\frac{1}{3} x + \frac{1}{5} x + \frac{1}{6} x = \frac{21}{40}

\frac{10 + 6 + 5}{30} x = \frac{21}{40}

\frac{21}{30} x = \frac{21}{40}

x = \frac{21}{40} : \frac{21}{30}

x = \frac{21}{40} * \frac{30}{21}

x = \frac{1}{4} * \frac{3}{1}

x = \frac{3}{4}

\frac{1}{4} x + \frac{1}{6} x + \frac{1}{8} x = \frac{39}{56}

\frac{6 + 4 + 3}{24} x = \frac{39}{56}

\frac{13}{24} x = \frac{39}{56}

x = \frac{39}{56} : \frac{13}{24}

x = \frac{39}{56} * \frac{24}{13}

x = \frac{3}{7} * \frac{3}{1}

x = \frac{9}{7} = 1 \frac{2}{7}

ГДЗ Математика 6 класс Мерзляк, Полонский, Якир