13) (17/10 - 1/20) * 2/15

$$\left(\frac{17}{10} - \frac{1}{20}\right) \cdot \frac{2}{15} = \left(\frac{17 \cdot 2}{10 \cdot 2} - \frac{1}{20}\right) \cdot \frac{2}{15} = \left(\frac{34}{20} - \frac{1}{20}\right) \cdot \frac{2}{15} = \frac{33}{20} \cdot \frac{2}{15} = \frac{33 \cdot 2}{20 \cdot 15} = \frac{66}{300} = \frac{11}{50}$$

Ответ: 11/50