A person marked his goods at a price that would give him 40% profit but he declared a sale and allowed 20% discount on the marked price. What is the profit percentage of the person in the whole transaction ?

12%

Let the cost price of the article = 100

MP of the article = 100 × (\(\frac{140}{100}\) ) = 140

SP of the article = 140 × (\(\frac{80}{100}\)) = 112

Profit = 112 – 100 = 12

Profit percentage = \(\frac{12}{100}\) × 100 = 12%