б) $$(2 + 3\frac{11}{18}) \cdot (20 - 17\frac{9}{16}) = (2 + \frac{65}{18}) \cdot (20 - \frac{281}{16}) = (\frac{2}{1} + \frac{65}{18}) \cdot (\frac{20}{1} - \frac{281}{16}) = (\frac{2 \cdot 18}{1 \cdot 18} + \frac{65}{18}) \cdot (\frac{20 \cdot 16}{1 \cdot 16} - \frac{281}{16}) = (\frac{36}{18} + \frac{65}{18}) \cdot (\frac{320}{16} - \frac{281}{16}) = \frac{101}{18} \cdot \frac{39}{16} = \frac{101}{6} \cdot \frac{13}{16} = \frac{1313}{96} = 13\frac{65}{96}$$
Ответ: $$13\frac{65}{96}$$