4.181 Выполните действия: a) (–0,28 + (–0,137)) + (–0,431 + (–0,256)) б) $$\left(-2\frac{2}{3} + \left(-3\frac{7}{12}\right)\right) + \left(-5\frac{1}{2} + \left(-2\frac{3}{8}\right)\right)$$

a) (–0,28 + (–0,137)) + (–0,431 + (–0,256)) = -0,28 - 0,137 - 0,431 - 0,256 = -1,104 б) $$\left(-2\frac{2}{3} + \left(-3\frac{7}{12}\right)\right) + \left(-5\frac{1}{2} + \left(-2\frac{3}{8}\right)\right) = \left(-\frac{8}{3} - \frac{43}{12}\right) + \left(-\frac{11}{2} - \frac{19}{8}\right) = \left(-\frac{32}{12} - \frac{43}{12}\right) + \left(-\frac{44}{8} - \frac{19}{8}\right) = -\frac{75}{12} - \frac{63}{8} = -\frac{150}{24} - \frac{189}{24} = -\frac{339}{24} = -\frac{113}{8} = -14\frac{1}{8}$$