A dealer offers a cash discount of 20% and still makes a profit of 20%, when he further allows 16 articles to a dozen to a particularly sticky bargainer. How much percent above the cost price were his wares listed?

Answer: Option A

Let the CP of the article be Rs. x, since he earns a profit of 20%, hence SP = X + 20% of X = 1.2x
It is given that he incurs loss by selling 16 articles at the cost of 12 articles [loss = $$\frac{16-12}{16}$$  = 25%]
His selling price = SP - 25% of SP = SP × 0.75
Hence, SP × 0.75 = 1.2X
Or, SP = $$\frac{1.2\times \text{x}}{0.75}$$  = 1.6X
This SP is arrived after giving a discount of 20% on MP.
Let MP = Y
Y - 20% of Y = SP
0.80Y = 1.6X
Y = 2X
It means that the article has been marked 100% above the cost price. Or Marked Price was twice of cost price.