\( \frac{1}{3} \) of A = 20% of B.

• \( \frac{A}{3} = \frac{20}{100} B = \frac{1}{5} B \)
• Multiply both sides by 15: 5A = 3B
• \( \frac{A}{B} = \frac{3}{5} \), so A : B = 3 : 5

Final Answer: 3 : 5