1. Stating the problem: Solve for $x$ in the proportion $$\frac{2}{5} = \frac{x}{20}$$. 2. Formula used: In a proportion $\frac{a}{b} = \frac{c}{d}$, the cross products are equal, so $a \times d = b \times c$. 3. Apply cross multiplication: $$2 \times 20 = 5 \times x$$ 4. Simplify the multiplication: $$40 = 5x$$ 5. Solve for $x$ by dividing both sides by 5: $$\frac{40}{\cancel{5}} = \frac{5x}{\cancel{5}}$$ $$8 = x$$ 6. Final answer: $$x = 8$$