A shopkeeper sold an article at 20% discount and earned a profit of 4%. By what percent the marked price of the article more than the cost price of the article ?

Let the cost price of each article = Rs. $$100x$$

=> Selling price = $$\frac{104}{100} \times 100x = 104x$$ ------------------Eqn(1)

Let the marked price = Rs. $$100y$$

Selling price of article after 20% discount = $$\frac{80}{100} \times 100y = 80y$$ ------------Eqn(2)

Comparing eqns(1) & (2), we get :

=> $$104x = 80y$$

=> $$\frac{y}{x} = \frac{104}{80} = \frac{13}{10}$$

$$\therefore$$ Required % by which marked price is more than the cost price

= $$\frac{13 - 10}{10} \times 100 = 30 \%$$