1. **Problem:** Compare the fractions $\frac{3}{4}$ and $\frac{5}{8}$. 2. **Formula and rule:** To compare fractions with different denominators, use cross multiplication: $$a/b \quad \text{and} \quad c/d \implies ad \quad \text{vs} \quad bc$$ If $ad > bc$, then $\frac{a}{b} > \frac{c}{d}$; if $ad < bc$, then $\frac{a}{b} < \frac{c}{d}$. 3. **Apply cross multiplication:** Calculate $3 \times 8 = 24$ and $5 \times 4 = 20$. 4. **Compare results:** Since $24 > 20$, we conclude $$\frac{3}{4} > \frac{5}{8}$$ 5. **Explanation:** Cross multiplication helps us compare fractions without finding a common denominator by comparing the products of numerator and opposite denominator. This method is quick and reliable.