4. Решите уравнение: a) $$3\frac{4}{15} + y = 7\frac{11}{15}$$; б) $$5\frac{4}{13} - x = 4\frac{5}{13}$$.

a) $$3\frac{4}{15} + y = 7\frac{11}{15}$$ $$y = 7\frac{11}{15} - 3\frac{4}{15}$$ $$y = (7 - 3) + (\frac{11}{15} - \frac{4}{15})$$ $$y = 4 + \frac{11 - 4}{15}$$ $$y = 4 + \frac{7}{15}$$ $$y = 4\frac{7}{15}$$ б) $$5\frac{4}{13} - x = 4\frac{5}{13}$$ $$x = 5\frac{4}{13} - 4\frac{5}{13}$$ $$x = (5 - 4) + (\frac{4}{13} - \frac{5}{13})$$ $$x = 1 - \frac{1}{13}$$ $$x = \frac{13}{13} - \frac{1}{13}$$ $$x = \frac{12}{13}$$ Ответ: a) $$y = 4\frac{7}{15}$$; б) $$x = \frac{12}{13}$$