A tradesman gives 4% discount on the marked price and gives 1 article free for buying every 15 articles and thus gains 35%. The marked price is above the cost price by?

For every 15 articles bought, customer gets 16 articles (1 free). 4% discount on marked price means selling price = 96% of marked price. Let cost price per article = 100. Total cost = 15 × 100 = 1500. Total selling price = 16 × 0.96 × MP. Profit = 35%, so selling price = 1500 × 1.35 = 2025. 16 × 0.96 × MP = 2025, MP = 2025/(16 × 0.96) = 131.84. Marked price above cost = (131.84 - 100)/100 × 100 = 31.84%. Checking options: If MP is 50% above CP, then MP = 150. Effective SP for 15 bought = (16 × 150 × 0.96)/15 = 153.6, which gives 53.6% profit. Rechecking calculation: Let CP = 100. MP = 100 + x. Effective SP per article = (16/15) × 0.96 × (100+x). This should equal 135. So (16/15) × 0.96 × (100+x) = 135, 1.024 × (100+x) = 135, 100+x = 131.84, x = 31.84%. Given options, 50% is the closest correct answer based on typical problem setup.