б) \(\frac{2a}{8ab}, \frac{15mkt}{34mt}, \frac{18dcm}{45bdmk}, \frac{xy}{4mnxy};\)

Решение:

Сократим каждую дробь:

1. \( \frac{2a}{8ab} = \frac{2a}{2a \cdot 4b} = \frac{1}{4b} \)
2. \( \frac{15mkt}{34mt} = \frac{15k \cdot mt}{34 \cdot mt} = \frac{15k}{34} \)
3. \( \frac{18dcm}{45bdmk} = \frac{2 \cdot 9 \cdot d \cdot c \cdot m}{5 \cdot 9 \cdot b \cdot d \cdot m \cdot k} = \frac{2c}{5bk} \)
4. \( \frac{xy}{4mnxy} = \frac{xy}{4mn \cdot xy} = \frac{1}{4mn} \)

Ответ: \( \frac{1}{4b}, \frac{15k}{34}, \frac{2c}{5bk}, \frac{1}{4mn} \).