a) \(A = \left[\right. \frac{2}{7} \left(\right. \frac{1}{4} - \frac{1}{3} \left.\right) \left]\right. : \left[\right. \frac{2}{7} \left(\right. \frac{1}{3} - \frac{2}{5} \left.\right) \left]\right. = \left(\right. \frac{1}{4} - \frac{1}{3} \left.\right) : \left(\right. \frac{1}{3} - \frac{2}{5} \left.\right) = 1 \frac{1}{4}\).
b) \(B = \frac{\frac{3}{4} \left(\right. \frac{1}{5} - \frac{2}{7} - \frac{1}{3} + \frac{2}{7} \left.\right)}{\frac{1}{5} \left(\right. \frac{2}{7} + \frac{1}{3} \left.\right) - \frac{1}{3} \left(\right. \frac{2}{7} + \frac{1}{3} \left.\right)} = \frac{\frac{3}{4} \left(\right. \frac{1}{5} - \frac{1}{3} \left.\right)}{\left(\right. \frac{1}{5} - \frac{1}{3} \left.\right) \left(\right. \frac{2}{7} + \frac{1}{3} \left.\right)} = 1 \frac{11}{52}\).

a) \(A=\frac{3}{5}.\frac{6}{7}+\frac{3}{7}.\frac{3}{5}-\frac{2}{7}.\frac{3}{5}\)
\(= \frac{3}{5} \cdot \left(\right. \frac{6}{7} + \frac{3}{7} - \frac{2}{7} \left.\right) = \frac{3}{5}\)
b) \(B=\left(\right.-13\cdot\frac{2}{5}+\frac{- 2}{9}\cdot\frac{2}{5}+\frac{2}{5}\cdot\frac{11}{9}\left.\right)\cdot\frac{5}{2}\)
\(= \left(\right. - 13 - \frac{2}{9} + \frac{11}{9} \left.\right) \cdot \frac{2}{5} \cdot \frac{5}{2} = - 13 + \left(\right. \frac{11}{9} - \frac{2}{9} \left.\right) = - 12.\)
c) \(C = \left(\right. \frac{- 4}{5} + \frac{5}{7} \left.\right) \cdot \frac{3}{2} + \left(\right. \frac{- 1}{5} + \frac{2}{7} \left.\right) \cdot \frac{3}{2} = \left(\right. \frac{- 4}{5} + \frac{5}{7} + \frac{- 1}{5} + \frac{2}{7} \left.\right) \cdot \frac{3}{2} = \left(\right. \left(\right. \frac{- 4}{5} + \frac{- 1}{5} \left.\right) + \left(\right. \frac{5}{7} + \frac{2}{7} \left.\right) \left.\right) \cdot \frac{3}{2} = 0.\)
d) \(D = \frac{4}{9} : \left(\right. \frac{1}{15} - \frac{10}{15} \left.\right) + \frac{4}{9} : \left(\right. \frac{2}{22} - \frac{5}{22} \left.\right)\)
\(=\frac{4}{9}:\frac{- 3}{5}+\frac{4}{9}:\frac{- 3}{22}=\frac{4}{9}\cdot\frac{- 5}{3}+\frac{4}{9}.\frac{- 22}{3}\)
\(=\frac{4}{9}\cdot\left(\right.\frac{- 5}{3}+\frac{- 22}{3}\left.\right)=\frac{4}{9}.\frac{- 27}{3}=-4.\)

a) \(A=\frac{3}{5}.\frac{6}{7}+\frac{3}{7}.\frac{3}{5}-\frac{2}{7}.\frac{3}{5}\)
\(= \frac{3}{5} \cdot \left(\right. \frac{6}{7} + \frac{3}{7} - \frac{2}{7} \left.\right) = \frac{3}{5}\)
b) \(B=\left(\right.-13\cdot\frac{2}{5}+\frac{- 2}{9}\cdot\frac{2}{5}+\frac{2}{5}\cdot\frac{11}{9}\left.\right)\cdot\frac{5}{2}\)
\(= \left(\right. - 13 - \frac{2}{9} + \frac{11}{9} \left.\right) \cdot \frac{2}{5} \cdot \frac{5}{2} = - 13 + \left(\right. \frac{11}{9} - \frac{2}{9} \left.\right) = - 12.\)
c) \(C = \left(\right. \frac{- 4}{5} + \frac{5}{7} \left.\right) \cdot \frac{3}{2} + \left(\right. \frac{- 1}{5} + \frac{2}{7} \left.\right) \cdot \frac{3}{2} = \left(\right. \frac{- 4}{5} + \frac{5}{7} + \frac{- 1}{5} + \frac{2}{7} \left.\right) \cdot \frac{3}{2} = \left(\right. \left(\right. \frac{- 4}{5} + \frac{- 1}{5} \left.\right) + \left(\right. \frac{5}{7} + \frac{2}{7} \left.\right) \left.\right) \cdot \frac{3}{2} = 0.\)
d) \(D = \frac{4}{9} : \left(\right. \frac{1}{15} - \frac{10}{15} \left.\right) + \frac{4}{9} : \left(\right. \frac{2}{22} - \frac{5}{22} \left.\right)\)
\(=\frac{4}{9}:\frac{- 3}{5}+\frac{4}{9}:\frac{- 3}{22}=\frac{4}{9}\cdot\frac{- 5}{3}+\frac{4}{9}.\frac{- 22}{3}\)
\(=\frac{4}{9}\cdot\left(\right.\frac{- 5}{3}+\frac{- 22}{3}\left.\right)=\frac{4}{9}.\frac{- 27}{3}=-4.\)

a) \(A = \left(\right. \frac{1}{3} + \frac{2}{3} \left.\right) - \left(\right. \frac{8}{15} + \frac{7}{15} \left.\right) + \left(\right. \frac{- 1}{7} + 1 \frac{1}{7} \left.\right) = 1 - 1 + 1 = 1\);
b) \(B = \left(\right. 0.25 - 1 \frac{1}{4} \left.\right) + \left(\right. \frac{3}{5} + \frac{2}{5} \left.\right) - \frac{1}{8}\)
\(= \left(\right. \frac{1}{4} - 1 - \frac{1}{4} \left.\right) + 1 - \frac{1}{8} = \frac{- 1}{8}\).