1 Вычислите: а) \frac{16}{21}:\frac{12}{35}-2. б) \frac{3}{16}\cdot(\frac{4}{9}-\frac{8}{27}).

а) Вычислим:

$$\frac{16}{21}:\frac{12}{35}-2 = \frac{16}{21} \cdot \frac{35}{12} - 2 = \frac{16 \cdot 35}{21 \cdot 12} - 2 = \frac{4 \cdot 5}{3 \cdot 3} - 2 = \frac{20}{9} - 2 = \frac{20}{9} - \frac{18}{9} = \frac{20-18}{9} = \frac{2}{9}$$.

б) Вычислим:

$$\frac{3}{16} \cdot (\frac{4}{9}-\frac{8}{27}) = \frac{3}{16} \cdot (\frac{4 \cdot 3}{9 \cdot 3} - \frac{8}{27}) = \frac{3}{16} \cdot (\frac{12}{27} - \frac{8}{27}) = \frac{3}{16} \cdot \frac{12-8}{27} = \frac{3}{16} \cdot \frac{4}{27} = \frac{3 \cdot 4}{16 \cdot 27} = \frac{1 \cdot 1}{4 \cdot 9} = \frac{1}{36}$$.

Ответ: а) \frac{2}{9}; б) \frac{1}{36}