\[\frac{3}{8} + \frac{5}{9} + \frac{5}{8} + \frac{4}{9} = (\frac{3}{8} + \frac{5}{8}) + (\frac{5}{9} + \frac{4}{9}) = \frac{3+5}{8} + \frac{5+4}{9} = \frac{8}{8} + \frac{9}{9} = 1 + 1 = 2\]
\[\frac{4}{15} + \frac{3}{7} + \frac{11}{15} + \frac{6}{7} = (\frac{4}{15} + \frac{11}{15}) + (\frac{3}{7} + \frac{6}{7}) = \frac{4+11}{15} + \frac{3+6}{7} = \frac{15}{15} + \frac{9}{7} = 1 + \frac{9}{7} = 1 + \frac{7}{7} + \frac{2}{7} = 1 + 1 + \frac{2}{7} = 2\frac{2}{7}\]