2 Выполните действия: а) $$2\frac{2}{5} \cdot (\frac{11}{14} - \frac{3}{7})$$; б) $$(\frac{1}{3})^2 + (\frac{1}{3})^3$$

а) $$2\frac{2}{5} \cdot (\frac{11}{14} - \frac{3}{7})$$ $$2\frac{2}{5} = \frac{2 \cdot 5 + 2}{5} = \frac{12}{5}$$ $$\frac{11}{14} - \frac{3}{7} = \frac{11}{14} - \frac{3 \cdot 2}{7 \cdot 2} = \frac{11}{14} - \frac{6}{14} = \frac{5}{14}$$ $$\frac{12}{5} \cdot \frac{5}{14} = \frac{12 \cdot 5}{5 \cdot 14} = \frac{60}{70} = \frac{6}{7}$$ б) $$(\frac{1}{3})^2 + (\frac{1}{3})^3$$ $$(\frac{1}{3})^2 = \frac{1}{3} \cdot \frac{1}{3} = \frac{1}{9}$$ $$(\frac{1}{3})^3 = \frac{1}{3} \cdot \frac{1}{3} \cdot \frac{1}{3} = \frac{1}{27}$$ $$\frac{1}{9} + \frac{1}{27} = \frac{1 \cdot 3}{9 \cdot 3} + \frac{1}{27} = \frac{3}{27} + \frac{1}{27} = \frac{4}{27}$$