Вычислить: a) $$30\frac{16}{43} + 42\frac{19}{43} + 9\frac{8}{43}$$; б) $$180 - \frac{179}{180}$$; в) $$\frac{\frac{5}{6}}{\frac{3}{9}}$$; г) $$\frac{3}{8} \cdot \frac{10}{11}$$

a) $$30\frac{16}{43} + 42\frac{19}{43} + 9\frac{8}{43} = (30 + 42 + 9) + \frac{16+19+8}{43} = 81 + \frac{43}{43} = 81 + 1 = 82$$ Ответ: 82 б) $$180 - \frac{179}{180} = \frac{180 \cdot 180 - 179}{180} = \frac{32400 - 179}{180} = \frac{32221}{180} = 179\frac{181}{180} = 179 + \frac{180}{180} + \frac{1}{180} = 180\frac{1}{180}$$ Ответ: $$180\frac{1}{180}$$ в) $$\frac{\frac{5}{6}}{\frac{3}{9}} = \frac{5}{6} : \frac{3}{9} = \frac{5}{6} \cdot \frac{9}{3} = \frac{5}{2} \cdot \frac{3}{3} = \frac{5}{2} = 2\frac{1}{2} = 2,5$$ Ответ: 2,5 г) $$\frac{3}{8} \cdot \frac{10}{11} = \frac{3 \cdot 10}{8 \cdot 11} = \frac{3 \cdot 5}{4 \cdot 11} = \frac{15}{44}$$ Ответ: $$\frac{15}{44}$$