1. **Stating the problem:** Solve the equation $$\frac{x}{6} = \frac{15}{18}$$ for $x$. 2. **Formula and rules:** To solve for $x$ in a proportion $\frac{a}{b} = \frac{c}{d}$, use cross multiplication: $$a \times d = b \times c$$. 3. **Apply cross multiplication:** $$x \times 18 = 6 \times 15$$ 4. **Calculate the right side:** $$x \times 18 = 90$$ 5. **Isolate $x$ by dividing both sides by 18:** $$x = \frac{90}{18}$$ 6. **Show cancellation:** $$x = \frac{\cancel{90}}{\cancel{18}} = 5$$ 7. **Final answer:** $$x = 5$$ This matches one of the multiple choice answers, confirming the solution.