5 10 5 +4 9

Выполним сложение:

$$5\frac{10}{21} + 4\frac{5}{6} = \frac{5 \cdot 21 + 10}{21} + \frac{4 \cdot 6 + 5}{6} = \frac{105 + 10}{21} + \frac{24 + 5}{6} = \frac{115}{21} + \frac{29}{6} = \frac{115 \cdot 2}{21 \cdot 2} + \frac{29 \cdot 7}{6 \cdot 7} = \frac{230}{42} + \frac{203}{42} = \frac{230 + 203}{42} = \frac{433}{42} = 10 \frac{13}{42}$$

Ответ: $$10 \frac{13}{42}$$