№3. Выполните сложение: $$4\frac{15}{18} - 2\frac{17}{18} = ?$$ $$6\frac{20}{63} - 5\frac{41}{63} = ?$$ $$15\frac{7}{18} - 7\frac{13}{18} = ?$$

**Решение:** 1. $$4\frac{15}{18} - 2\frac{17}{18} = 3\frac{33}{18} - 2\frac{17}{18} = (3-2) + (\frac{33}{18} - \frac{17}{18}) = 1 + \frac{16}{18} = 1\frac{8}{9}$$ 2. $$6\frac{20}{63} - 5\frac{41}{63} = 5\frac{83}{63} - 5\frac{41}{63} = (5-5) + (\frac{83}{63} - \frac{41}{63}) = 0 + \frac{42}{63} = \frac{2}{3}$$ 3. $$15\frac{7}{18} - 7\frac{13}{18} = 14\frac{25}{18} - 7\frac{13}{18} = (14 - 7) + (\frac{25}{18} - \frac{13}{18}) = 7 + \frac{12}{18} = 7 + \frac{2}{3} = 7\frac{2}{3}$$