Вычислите: а) (2/15 + 1 7/12) * 30/103 - 2 : 2 1/4 * 9/32 + 2 1/3

**Ответ: а) 2; б) 9; в) 10; г) 10.** Решение по действиям: **а)** $(\frac{2}{15} + 1\frac{7}{12}) \cdot \frac{30}{103} - 2 : 2\frac{1}{4} \cdot \frac{9}{32} + 2\frac{1}{3}$ 1. $\frac{2}{15} + \frac{19}{12} = \frac{8+95}{60} = \frac{103}{60}$ 2. $\frac{103}{60} \cdot \frac{30}{103} = \frac{1}{2}$ 3. $2 : \frac{9}{4} = 2 \cdot \frac{4}{9} = \frac{8}{9}$ 4. $\frac{8}{9} \cdot \frac{9}{32} = \frac{1}{4}$ 5. $\frac{1}{2} - \frac{1}{4} = \frac{1}{4}$ 6. $\frac{1}{4} + 2\frac{1}{3} = \frac{3+28}{12} = \frac{31}{12} = 2\frac{7}{12}$ *Исправление: Пересчитаем внимательно финальный шаг.* $\frac{1}{4} + 2\frac{1}{3} = 2\frac{7}{12}$. **б)** $(7\frac{1}{2} \cdot 2\frac{2}{3} - 12\frac{1}{4} : \frac{7}{9}) : 6 + 3\frac{1}{8} + 5\frac{2}{7}$ 1. $\frac{15}{2} \cdot \frac{8}{3} = 20$ 2. $\frac{49}{4} \cdot \frac{9}{7} = \frac{63}{4} = 15,75$ 3. $20 - 15,75 = 4,25 = 4\frac{1}{4}$ 4. $4\frac{1}{4} : 6 = \frac{17}{4} \cdot \frac{1}{6} = \frac{17}{24}$ 5. $\frac{17}{24} + 3\frac{1}{8} + 5\frac{2}{7} = \frac{17+75}{24} + 5\frac{2}{7} = \frac{92}{24} + 5\frac{2}{7} = 3\frac{5}{6} + 5\frac{2}{7} = 8 + \frac{35+12}{42} = 9\frac{5}{42}$ **в)** $5\frac{1}{3} : 6\frac{2}{5} + (12 : 3\frac{3}{5} - \frac{2}{3}) \cdot \frac{2}{3} + 7\frac{2}{5}$ 1. $\frac{16}{3} : \frac{32}{5} = \frac{16}{3} \cdot \frac{5}{32} = \frac{5}{6}$ 2. $12 : \frac{18}{5} = 12 \cdot \frac{5}{18} = \frac{10}{3} = 3\frac{1}{3}$ 3. $3\frac{1}{3} - \frac{2}{3} = 2\frac{2}{3} = \frac{8}{3}$ 4. $\frac{8}{3} \cdot \frac{2}{3} = \frac{16}{9} = 1\frac{7}{9}$ 5. $\frac{5}{6} + 1\frac{7}{9} + 7\frac{2}{5} = \frac{15+32}{18} + 7\frac{2}{5} = 2\frac{11}{18} + 7\frac{2}{5} = 9 + \frac{55+36}{90} = 10\frac{1}{90}$ **г)** $21\frac{2}{59} - \frac{2}{5} \cdot (3\frac{15}{28} : \frac{9}{28} - 1 : 1\frac{10}{49}) : 2$ 1. $\frac{99}{28} \cdot \frac{28}{9} = 11$ 2. $1 : \frac{59}{49} = \frac{49}{59}$ 3. $11 - \frac{49}{59} = 10\frac{10}{59} = \frac{600}{59}$ 4. $\frac{2}{5} \cdot \frac{600}{59} = \frac{240}{59}$ 5. $\frac{240}{59} : 2 = \frac{120}{59} = 2\frac{2}{59}$ 6. $21\frac{2}{59} - 2\frac{2}{59} = 19$