б) \(\left(-6\frac{5}{9} + 5\frac{5}{18}\right) - 2\frac{1}{2} = \left(-\frac{59}{9} + \frac{95}{18}\right) - \frac{5}{2} = \left(-\frac{118}{18} + \frac{95}{18}\right) - \frac{5}{2} = -\frac{23}{18} - \frac{5}{2} = -\frac{23}{18} - \frac{45}{18} = -\frac{68}{18} = -\frac{34}{9} = -3\frac{7}{9}\)