a, \(-2,5\%-\left[1-\left(\frac{2}{3}\right)^2\right]+\left(1-\frac{4}{9}\right)\\ =\frac{-1}{40}-\left[1-\frac{4}{9}\right]+\left(1-\frac{4}{9}\right)\\ =\frac{-1}{40}+\left[\left(1-\frac{4}{9}\right)-\left(1-\frac{4}{9}\right)\right]\\ =\frac{-1}{40}+0\\ =\frac{-1}{40}\)
b, \(5\frac{1}{2}-14\frac{3}{7}:\frac{9}{13}-3\frac{4}{7}:\frac{9}{13}\\ =5\frac{1}{2}-\left(14\frac{3}{7}:\frac{9}{13}+3\frac{4}{7}:\frac{9}{13}\right)\\ =5\frac{1}{2}-\left[\left(14\frac{3}{7}+3\frac{4}{7}\right):\frac{9}{13}\right]\\ =5\frac{1}{2}-\left(18:\frac{9}{13}\right)\\ =5\frac{1}{2}-\left(18\cdot\frac{13}{9}\right)\\ =\frac{11}{2}-26\\ =\frac{-41}{2}\)
c, \(\left(1+2\frac{1}{4}-3\frac{1}{3}\right):\left(1+3\frac{1}{2}-4\frac{7}{12}\right)\\ =\left(3\frac{1}{4}-3\frac{1}{3}\right):\left(4\frac{1}{2}-4\frac{7}{12}\right)\\ =\frac{-1}{12}:\frac{-1}{12}\\ =1\)
