1. **State the problem:** Subtract the fractions $\frac{9}{8} - \frac{3}{4}$. Make sure the answer is fully reduced. 2. **Formula and rules:** To subtract fractions, find a common denominator, convert each fraction, then subtract the numerators. 3. **Find the least common denominator (LCD):** $$\text{LCD of } 8 \text{ and } 4 = 8$$ 4. **Convert fractions to have the LCD:** $$\frac{9}{8} \text{ stays the same}$$ $$\frac{3}{4} = \frac{3 \times 2}{4 \times 2} = \frac{6}{8}$$ 5. **Subtract the numerators:** $$\frac{9}{8} - \frac{6}{8} = \frac{9 - 6}{8} = \frac{3}{8}$$ 6. **Simplify the fraction:** $\frac{3}{8}$ is already in simplest form. **Final answer:** $$\boxed{\frac{3}{8}}$$