A shopkeeper purchased 150 identical pieces of calculators at the rate of Rs. 250 each. He spent an amount of Rs. 2500 on transport and packing. He fixed the labelled price of each calculator at Rs. 320. However, he decided to give a discount of 5% on labelled price. What is the percentage profit earned by him ?

$$\eqalign{ & {\text{Cost of each calculator}} \cr & {\text{ = Rs}}{\text{.}}\left( {250 + \frac{{2500}}{{150}}} \right) \cr & = {\text{Rs}}{\text{. 266}}\frac{2}{3} \cr & {\text{S}}{\text{.P}}{\text{. of each calculator}} \cr & {\text{ = Rs}}{\text{.}}\left( {\frac{{95}}{{100}} \times 320} \right) \cr & = {\text{Rs}}{\text{. 304}}{\text{}} \cr & \therefore {\text{ Profit }}\% \cr & {\text{ = }}\left( {\frac{{112}}{3} \times \frac{3}{{800}} \times 100} \right)\% \cr & = 14\% \cr} $$