в) $$7\frac{4}{19}\cdot 6\frac{1}{4}+4\frac{15}{19}$$

в) $$7\frac{4}{19}\cdot 6\frac{1}{4}+4\frac{15}{19} = \frac{137}{19}\cdot \frac{25}{4}+4\frac{15}{19} = \frac{3425}{76} + \frac{91}{19} = \frac{3425}{76} + \frac{364}{76} = \frac{3789}{76} = 49\frac{65}{76}$$

Ответ: $$49\frac{65}{76}$$