Применим теорему синусов: $$\frac{AC}{\sin B} = \frac{BC}{\sin A}$$
$$\frac{AC}{\sin 30^{\circ}} = \frac{6\sqrt{2}}{\sin 45^{\circ}}$$
$$AC = \frac{6\sqrt{2} \cdot \sin 30^{\circ}}{\sin 45^{\circ}} = \frac{6\sqrt{2} \cdot \frac{1}{2}}{\frac{\sqrt{2}}{2}} = \frac{6\sqrt{2}}{2} \cdot \frac{2}{\sqrt{2}} = 6$$
Ответ: $$AC = 6$$