A shopkeeper makes a profit of 12.5% after allowing a discount of 10% on the marked price of an article. Find his profit percentage if the article is sold at the marked price, allowing no discount.

25%

        CP                    MP

      100 - D%           100 + P%

     100 - 10%           100 + 12.5%

         90                      112.5

Profit when no discount is allowed = 112.5 - 90 = 22.5

Profit % = 22.5 × \(\frac{100}{90}\) = 25%