a) $$38 \frac{1}{8} + 4 \frac{5}{24} = 38 \frac{3}{24} + 4 \frac{5}{24} = 42 \frac{8}{24} = 42 \frac{1}{3}$$
б) $$4 \frac{19}{75} + 6 \frac{17}{45} = 4 \frac{19 \cdot 3}{75 \cdot 3} + 6 \frac{17 \cdot 5}{45 \cdot 5} = 4 \frac{57}{225} + 6 \frac{85}{225} = 10 \frac{142}{225}$$
Ответ: a) $$42 \frac{1}{3}$$; б) $$10 \frac{142}{225}$$