5.14 Найдите значение суммы: a) $-6\frac{2}{6} + 4\frac{5}{9}$; б) $2\frac{4}{15} - 3\frac{11}{20}$;

a) $-6\frac{2}{6} + 4\frac{5}{9} = -6\frac{1}{3} + 4\frac{5}{9} = -\frac{19}{3} + \frac{41}{9} = -\frac{57}{9} + \frac{41}{9} = -\frac{16}{9} = -1\frac{7}{9}$ б) $2\frac{4}{15} - 3\frac{11}{20} = \frac{34}{15} - \frac{71}{20} = \frac{34*4}{15*4} - \frac{71*3}{20*3} = \frac{136}{60} - \frac{213}{60} = -\frac{77}{60} = -1\frac{17}{60}$