207. Решите уравнение: a) \(x + \frac{13}{31} = \frac{14}{31}\); б) \(\frac{6}{15} + y = \frac{8}{15}\); в) \(z - \frac{8}{21} = \frac{11}{21}\); г) \(\frac{7}{20} - k = \frac{1}{20}\).

Решим уравнения:

a) \(x + \frac{13}{31} = \frac{14}{31}\)
\(x = \frac{14}{31} - \frac{13}{31}\)
\(x = \frac{14-13}{31}\)
\(x = \frac{1}{31}\)

б) \(\frac{6}{15} + y = \frac{8}{15}\)
\(y = \frac{8}{15} - \frac{6}{15}\)
\(y = \frac{8-6}{15}\)
\(y = \frac{2}{15}\)

в) \(z - \frac{8}{21} = \frac{11}{21}\)
\(z = \frac{11}{21} + \frac{8}{21}\)
\(z = \frac{11+8}{21}\)
\(z = \frac{19}{21}\)

г) \(\frac{7}{20} - k = \frac{1}{20}\)
\(k = \frac{7}{20} - \frac{1}{20}\)
\(k = \frac{7-1}{20}\)
\(k = \frac{6}{20} = \frac{3}{10}\)

Ответ: a) \(x = \frac{1}{31}\); б) \(y = \frac{2}{15}\); в) \(z = \frac{19}{21}\); г) \(k = \frac{3}{10}\)