Profit on 5 articles is equal to discount on 15 articles. Then find the ratio of cost price and marked price where profit is 15%. 5 वस्तुओं पर होने वाला लाभ, 15 वस्तुओं पर दिए गए छूट के बराबर है, तो क्रय मूल्य तथा अंकित मूल्य का अनुपात बताइये यदि लाभ 15% हो।

Let CP = c, MP = m. Profit = 15%, so SP = 1.15c. Discount = (m - SP)/m = (m - 1.15c)/m = 1 - 1.15(c/m). Profit on 5 = 5 × 0.15c = 0.75c. Discount on 15 = 15 × discount on 1 = 15 × (m - 1.15c). Equating: 0.75c = 15(m - 1.15c). Solving gives c/m = 50/59. Ratio CP:MP = 50:59. Options B, C, D with ratios 40:49, 60:69, 70:79 don't satisfy the condition.