Odpowiedź:
[tex]a) \: 15 - ( - 11) - 15 - 11 = 15 + 11 - 15 - 11 = 0 \\ \\ b) - 10 - 7 - ( - 7) - 18 = - 17 + 7 - 18 = - 10 - 18 = - 28 \\ \\ c) - \frac{1}{9} + \frac{2}{3} + \frac{5}{9} - \frac{5}{6} - \frac{2}{3} = - \frac{2}{18} + \frac{12}{18} + \frac{10}{18} - \frac{15}{18} - \frac{12}{18} = - \frac{7}{18} \\ \\ d) - \frac{2}{7} + \frac{3}{8} - \frac{1}{2} + \frac{2}{7} - \frac{1}{4} + \frac{1}{2} = \frac{3}{8} - \frac{1}{4} = \frac{3}{8} - \frac{2}{8} = \frac{1}{8} [/tex]