$$\frac{15}{16} : \frac{3}{8} \cdot \frac{3}{4} = \frac{15}{16} \cdot \frac{8}{3} \cdot \frac{3}{4} = \frac{15}{16} \cdot \frac{8}{4} = \frac{15}{2 \cdot 8} \cdot \frac{8}{4} = \frac{15}{2} \cdot \frac{1}{4} = \frac{15}{8}$$
Ответ: \frac{15}{8}