2. Вычислите:1)$$\frac{3}{8}+2\frac{1}{6}$$; 2) $$5\frac{11}{12}-3\frac{7}{18}$$; 3) $$1\frac{5}{7}:6\frac{1}{8}$$; 4) $$40\frac{21}{4}:3\frac{3}{4}$$.

1) $$\frac{3}{8}+2\frac{1}{6} = \frac{3}{8}+\frac{13}{6} = \frac{3 \cdot 3}{8 \cdot 3}+\frac{13 \cdot 4}{6 \cdot 4} = \frac{9}{24}+\frac{52}{24} = \frac{9+52}{24} = \frac{61}{24} = 2\frac{13}{24}$$

2) $$5\frac{11}{12}-3\frac{7}{18} = \frac{71}{12} - \frac{61}{18} = \frac{71 \cdot 3}{12 \cdot 3} - \frac{61 \cdot 2}{18 \cdot 2} = \frac{213}{36} - \frac{122}{36} = \frac{213-122}{36} = \frac{91}{36} = 2\frac{19}{36}$$

3) $$1\frac{5}{7}:6\frac{1}{8} = \frac{12}{7} : \frac{49}{8} = \frac{12}{7} \cdot \frac{8}{49} = \frac{12 \cdot 8}{7 \cdot 49} = \frac{96}{343}$$

4) $$40\frac{21}{4}:3\frac{3}{4} = \frac{181}{4} : \frac{15}{4} = \frac{181}{4} \cdot \frac{4}{15} = \frac{181 \cdot 4}{4 \cdot 15} = \frac{181}{15} = 12 \frac{1}{15}$$

Ответ: 1) $$2\frac{13}{24}$$, 2) $$2\frac{19}{36}$$, 3) $$\frac{96}{343}$$, 4) $$12 \frac{1}{15}$$.