This is a simple question on the topic of Profit, Loss and Discount.
To work out this problem, let us remember that SP = CP (1+\(\frac{p}{100}\)) where ‘p’ represents the profit percentage. SP = MP(1-\(\frac{d}{100}\)) where MP represents the Marked Price (or also known as Retail price) and ‘d’ represents the discount percentage.
Let the MP be 100x. Then,
Amount of discount given = 15% of 100x = 15x. Therefore, SP = MP – Discount = 85x. This 85x represents 2% more than the cost price since there was a 2% profit.
That is, 85x = 102% of the CP. Therefore,
CP = \(\frac{85x * 100 }{ 102}\). Notice that 85 and 102 are both multiples of 17. This is an indicator that you will be able to cancel off these numbers and obtain a neat little number for CP which can be dealt further (rather than ending up with vulgar decimals); this should tell you that you are on the right track.
CP = \(\frac{500x }{ 6}\) or CP = \(\frac{250x }{ 3}\).
If she wants to make a profit of 20%, her selling price should be 120% of the CP. This means,
Intended selling price = \(\frac{6}{5}\) * \(\frac{250x }{ 3}\) = 100x. This is the MP (or the retail price) we assumed at the start. This means that she has to sell the article AT RETAIL PRICE to obtain a 20% profit.
The correct answer option is D.
Hope that helps!