3 \frac{\sqrt{30}·\sqrt{15}}{\sqrt{18}};

$$\frac{\sqrt{30} \cdot \sqrt{15}}{\sqrt{18}} = \frac{\sqrt{2 \cdot 15} \cdot \sqrt{15}}{\sqrt{2 \cdot 9}} = \frac{\sqrt{2} \cdot \sqrt{15} \cdot \sqrt{15}}{\sqrt{2} \cdot \sqrt{9}} = \frac{15}{\sqrt{9}} = \frac{15}{3} = 5$$

Ответ: 5