Выполните действия с дробями

518. Выполните действия: а) $$\frac{1}{3} + \frac{1}{5} = \frac{5}{15} + \frac{3}{15} = \frac{5+3}{15} = \frac{8}{15}$$ б) $$\frac{1}{3} - \frac{1}{4} = \frac{4}{12} - \frac{3}{12} = \frac{4-3}{12} = \frac{1}{12}$$ в) $$2\frac{1}{9} + 1\frac{1}{3} = 2\frac{1}{9} + 1\frac{3}{9} = 3\frac{1+3}{9} = 3\frac{4}{9}$$ г) $$2\frac{1}{2} - 1\frac{1}{3} = 2\frac{3}{6} - 1\frac{2}{6} = (2-1) + (\frac{3}{6} - \frac{2}{6}) = 1 + \frac{1}{6} = 1\frac{1}{6}$$ д) $$3 - 1\frac{2}{5} = 2\frac{5}{5} - 1\frac{2}{5} = (2-1) + (\frac{5}{5} - \frac{2}{5}) = 1 + \frac{3}{5} = 1\frac{3}{5}$$ е) $$\frac{2}{3} \cdot \frac{3}{4} = \frac{2 \cdot 3}{3 \cdot 4} = \frac{2}{4} = \frac{1}{2}$$ ж) $$\frac{4}{5} : \frac{1}{5} = \frac{4}{5} \cdot \frac{5}{1} = \frac{4 \cdot 5}{5 \cdot 1} = 4$$ з) $$\frac{5}{9} \cdot \frac{1}{3} = \frac{5 \cdot 1}{9 \cdot 3} = \frac{5}{27}$$ и) $$1\frac{1}{3} : \frac{3}{4} = \frac{4}{3} : \frac{3}{4} = \frac{4}{3} \cdot \frac{4}{3} = \frac{16}{9} = 1\frac{7}{9}$$ к) $$2\frac{1}{4} \cdot 1\frac{1}{3} = \frac{9}{4} \cdot \frac{4}{3} = \frac{9 \cdot 4}{4 \cdot 3} = \frac{9}{3} = 3$$