Sam purchased 20 dozens of toys at the rate of Rs. 375 per dozen. He sold each one of them at the rate of Rs. 33. What was his percentage profit?

$$\eqalign{ & {\text{Cost}}\,{\text{Price}}\,{\text{of}}\,{\text{1}}\,{\text{toy}} \cr & = Rs.\,\left( {\frac{{375}}{{12}}} \right) = Rs.\,31.25 \cr & {\text{Selling}}\,{\text{Price}}\,{\text{of}}\,{\text{1}}\,{\text{toy}}\, = \,Rs.\,33 \cr & {\text{So,}}\,{\text{Gain}}\, = \,Rs.\,\left( {33 - 31.25} \right) = Rs.\,1.75 \cr & \therefore {\text{Profit}}\,\% = \left( {\frac{{1.75}}{{31.25}} \times 100} \right)\% \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \frac{{28}}{5}\% = 5.6\% \, \cr} $$