в) $$7\frac{4}{19}\cdot6\frac{1}{4}+4\frac{15}{19}\cdot6\frac{1}{4};$$

в) $$7\frac{4}{19}\cdot6\frac{1}{4}+4\frac{15}{19}\cdot6\frac{1}{4} = \frac{137}{19} \cdot \frac{25}{4} + \frac{91}{19} \cdot \frac{25}{4} = \frac{25}{4} \cdot (\frac{137}{19} + \frac{91}{19}) = \frac{25}{4} \cdot \frac{228}{19} = \frac{25}{4} \cdot 12 = 25 \cdot 3 = 75$$

Ответ: 75