18. 24/2,7.

$$ \frac{24}{2,7} = \frac{24}{2,7} = \frac{240}{27} = \frac{3 \cdot 80}{3 \cdot 9} = \frac{80}{9} = 8 \frac{8}{9} $$

Ответ: $$8 \frac{8}{9} $$