A person sold his book for Rs. 96 and got a percentage profit equal to the cost price of the book. The cost price of the book is:

$$\eqalign{ & {\text{Let cost price}} = x \cr & \Rightarrow \frac{{x \times \left( {100 + x} \right)}}{{100}} = 96 \cr & \Rightarrow x \times \left( {100 + x} \right) = 9600 \cr & \Rightarrow x \times \left( {100 + x} \right) = 60 \times \left( {100 + 60} \right) \cr & \Rightarrow x = {\text{Rs}}{\text{. }}60{\text{ Ans}}{\text{.}} \cr} $$