) \(A = \left[\right. \frac{2}{7} \left(\right. \frac{1}{4} - \frac{1}{3} \left.\right) \left]\right. : \left[\right. \frac{2}{7} \left(\right. \frac{1}{3} - \frac{2}{5} \left.\right) \left]\right. = \left(\right. \frac{1}{4} - \frac{1}{3} \left.\right) : \left(\right. \frac{1}{3} - \frac{2}{5} \left.\right) = 1 \frac{1}{4}\).
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) \(A = \frac{3}{5} . \&\text{nbsp}; \frac{6}{7} + \frac{3}{7} . \&\text{nbsp}; \frac{3}{5} - \frac{2}{7} . \&\text{nbsp}; \frac{3}{5}\)
\(= \frac{3}{5} \cdot \left(\right. \frac{6}{7} + \frac{3}{7} - \frac{2}{7} \left.\right) = \frac{3}{5}\)
b) \(\&\text{nbsp}; B = \left(\right. - 13 \cdot \frac{2}{5} + \frac{- 2}{9} \cdot \frac{2}{5} + \frac{2}{5} \cdot \frac{11}{9} \left.\right) \cdot \frac{5}{2}\)
\(= \left(\right. - 13 - \frac{2}{9} + \frac{11}{9} \left.\right) \cdot \frac{2}{5} \cdot \frac{5}{2} = - 13 + \left(\right. \frac{11}{9} - \frac{2}{9} \left.\right) = - 12.\)
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) \(D = \frac{4}{9} : \left(\right. \frac{1}{15} - \frac{10}{15} \left.\right) + \frac{4}{9} : \left(\right. \frac{2}{22} - \frac{5}{22} \left.\right)\)
\(= \frac{4}{9} : \frac{- 3}{5} + \frac{4}{9} : \frac{- 3}{22} = \frac{4}{9} \cdot \frac{- 5}{3} + \frac{4}{9} . \&\text{nbsp}; \frac{- 22}{3}\)
\(= \frac{4}{9} \cdot \left(\right. \frac{- 5}{3} + \frac{- 22}{3} \left.\right) = \frac{4}{9} . \&\text{nbsp}; \frac{- 27}{3} = - 4.\)

a) \(P = \frac{2}{3} + \frac{1}{4} + \frac{3}{5} - \frac{7}{45} + \frac{5}{9} + \frac{1}{12} + \frac{1}{35}\) \(= \left(\right. \frac{2}{3} + \frac{1}{4} + \frac{1}{12} \left.\right) + \left(\right. \frac{5}{9} - \frac{7}{45} \left.\right) + \frac{3}{5} + \frac{1}{35} = 1 + \frac{4}{5} + \frac{3}{5} + \frac{1}{35} = 2 \frac{1}{35}\).

b) \(Q = \left(\right. 5 - 6 - 2 \left.\right) + \left(\right. - \frac{3}{4} - \frac{7}{4} + \frac{5}{4} \left.\right) + \left(\right. \frac{1}{5} + \frac{8}{5} - \frac{16}{5} \left.\right) = - \left(\right. 3 + \frac{5}{4} + \frac{7}{5} \left.\right)\) \(= - \&\text{nbsp}; \frac{113}{20}\).

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) \(B = \left(\right. 0.25 - 1 \frac{1}{4} \left.\right) + \left(\right. \frac{3}{5} + \frac{2}{5} \left.\right) - \frac{1}{8}\)
\(= \left(\right. \frac{1}{4} - 1 - \frac{1}{4} \left.\right) + 1 - \frac{1}{8} = \frac{- 1}{8}\).