Question

A 20% discount is applied when a book is sold by M for Rs. 240. If he made a profit of 20% on its sale, what was the cost price (CP) of the book?

Hint:

For profit and loss problems: \begin{itemize} \item Always distinguish between marked price, selling price, and cost price, \item Apply discount first, then profit or loss, \item Convert percentages into decimal form for easy calculation. \end{itemize}

Answer 1

Step 1: Let the marked price (MP) of the book be \(x\).
Step 2: A discount of 20% is given, so the selling price (SP) is: \[ \text{SP} = 0.8x \] Given that the selling price is Rs. 240: \[ 0.8x = 240 \Rightarrow x = 300 \]
Step 3: M makes a profit of 20%, so: \[ \text{SP} = 1.2 \times \text{CP} \]
Step 4: Substituting the value of SP: \[ 240 = 1.2 \times \text{CP} \Rightarrow \text{CP} = 200 \]
Step 5: Hence, the cost price of the book is Rs. 200.