How much percent more than the cost price should a shopkeeper mark his goods so that after allowing a discount of 25% on the marked price, he gain 20% ?

$$\eqalign{ & {\text{Let the cost price = Rs}}{\text{. 100}} \cr & {\text{Selling price = 120}}\% {\text{ of 100}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{ = Rs}}{\text{. 120}} \cr & {\text{Market price = 120}} \times \frac{{100}}{{75}}{\text{ }} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{ = Rs}}{\text{. 160}} \cr & {\text{Above }}\% {\text{ = }}\frac{{160 - 100}}{{100}} \times 100 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 60\% \cr} $$