8) 15 * 9/10

8) $$ 15 \cdot \frac{9}{10} = \frac{15 \cdot 9}{10} = \frac{5 \cdot 3 \cdot 9}{5 \cdot 2} = \frac{27}{2} = 13\frac{1}{2} $$

Ответ: $$13\frac{1}{2}$$