19. $$\frac{log_8 14}{log_{64} 14}$$

$$\frac{log_8 14}{log_{64} 14} = \frac{log_8 14}{log_{8^2} 14} = \frac{log_8 14}{\frac{1}{2}log_8 14} = \frac{1}{\frac{1}{2}} = 2$$

Ответ: $$2$$