Решите уравнение:
а) $х + \frac{4}{15} = \frac{2}{3} + \frac{2}{5}$;
б) $(\frac{4}{5} - х) + \frac{13}{20} = \frac{25}{30}$;
в) $y - \frac{5}{20} = \frac{5}{8} - \frac{3}{10}$;
г) $\frac{2}{3} - (\frac{7}{9} - a)= \frac{1}{3}$.
$х + \frac{4}{15} = \frac{2}{3} + \frac{2}{5}$
$х = \frac{2}{3} + \frac{2}{5} - \frac{4}{15} = \frac{10}{15} + \frac{6}{15} - \frac{4}{15} = \frac{12}{15} = \frac{4}{5}$
$(\frac{4}{5} - х) + \frac{13}{20} = \frac{25}{30}$
$х = \frac{4}{5} + \frac{13}{20} - \frac{25}{30} = \frac{48}{60} + \frac{39}{60} - \frac{50}{60} = \frac{37}{60}$
$y - \frac{5}{20} = \frac{5}{8} - \frac{3}{10}$
$y = \frac{5}{8} - \frac{3}{10} + \frac{5}{20} = \frac{25}{40} - \frac{12}{40} + \frac{10}{40} = \frac{23}{40}$
$\frac{2}{3} - (\frac{7}{9} - a) = \frac{1}{3}$
$\frac{2}{3} + \frac{7}{9} + a = \frac{1}{3}$
$a = \frac{1}{3} - \frac{2}{3} + \frac{7}{9} = -\frac{1}{3} + \frac{7}{9} = -\frac{3}{9} + \frac{7}{9} = \frac{4}{9}$
Пожауйста, оцените решение
