6:12 17

$${\frac{6}{17}} : 12 = {\frac{6}{17}} \cdot {\frac{1}{12}} = {\frac{6}{17 \cdot 12}} = {\frac{6}{17 \cdot 6 \cdot 2}} = {\frac{1}{17 \cdot 2}} = {\frac{1}{34}}$$

Ответ: $$\frac{1}{34}$$