1. The problem states that the shopkeeper makes a profit of 30% on the cost price by selling a book and the profit amount is Rs. 240. We need to find the cost price of the book. 2. Let the cost price be $x$. The profit is 30% of the cost price, so the profit can be written as $0.30x$. 3. According to the problem, the profit equals Rs. 240, so: $$0.30x = 240$$ 4. To find $x$, divide both sides of the equation by 0.30: $$x = \frac{240}{0.30}$$ 5. Calculate the division: $$x = 800$$ 6. Therefore, the cost price of the book is Rs. 800.