11) 4-5 2-1 2 - = = - 6-15 3-3 9

11) $$\frac{4 \cdot 5}{6 \cdot 15} = \frac{20}{90} = \frac{2}{9}$$

$$\frac{2 \cdot 1}{3 \cdot 3} = \frac{2}{9}$$

Ответ: $$\frac{2}{9}$$