Решение:

Для решения данных примеров необходимо выполнить сложение дробей.

1. a) $$\frac{3}{10} + (-\frac{7}{15}) = \frac{9}{30} - \frac{14}{30} = -\frac{5}{30} = -\frac{1}{6}$$
2. б) $$\frac{-15}{16} + (-\frac{3}{8}) = \frac{-15}{16} - \frac{6}{16} = \frac{-21}{16} = -1\frac{5}{16}$$
3. в) $$-3 \frac{5}{6} + (-1 \frac{2}{3}) = -\frac{23}{6} - \frac{5}{3} = -\frac{23}{6} - \frac{10}{6} = -\frac{33}{6} = -5\frac{3}{6} = -5\frac{1}{2}$$
4. г) $$-7 \frac{5}{7} + (-3 \frac{13}{21}) = -\frac{54}{7} - \frac{76}{21} = -\frac{162}{21} - \frac{76}{21} = -\frac{238}{21} = -11\frac{7}{21} = -11\frac{1}{3}$$

Ответ:

1. a) $$\frac{-1}{6}$$
2. б) $$-1\frac{5}{16}$$
3. в) $$-5\frac{1}{2}$$
4. г) $$-11\frac{1}{3}$$