б) 4/9 × 6/11 + 1/4 × 2/11 - 6/4 × 6/9 = 6/11

б) \(\frac{4}{9} \cdot \frac{6}{11} + \frac{1}{4} \cdot \frac{2}{11} - \frac{6}{4} \cdot \frac{6}{9} = \frac{24}{99} + \frac{2}{44} - \frac{36}{36} = \frac{8}{33} + \frac{1}{22} - 1 = \frac{16}{66} + \frac{3}{66} - \frac{66}{66} = \frac{19}{66} - \frac{66}{66} = -\frac{47}{66}\)

Ответ: -47/66