Supriya sold a washing machine for ₹ 8500. She incurred a loss of 15% in this transaction. At what price had she bought the washing machine?

### Concept & Formula The Cost Price (CP) can be calculated directly from the Selling Price (SP) and the loss percentage using the formula: $$CP = \frac{SP}{1 - \frac{Loss\%}{100}}$$ ### Step-by-Step Solution 1. Identify the given values: Selling Price ($SP$) = ₹ 8500 Loss Percentage = $15\%$ 2. Set up the equation: A loss of $15\%$ means the SP is $85\%$ of the CP. $$SP = 85\% \text{ of } CP$$ $$8500 = 0.85 \times CP$$ 3. Solve for CP: $$CP = \frac{8500}{0.85}$$ Multiply numerator and denominator by 100: $$CP = \frac{850000}{85} = 10000$$ ### Exam Strategy & Shortcut If SP represents $85\%$, then $85\% = 8500$. $1\% = 100$. $100\% \text{ (which is CP)} = 100 \times 100 = 10000$. ### Common Pitfall A very common mistake is calculating $15\%$ of the Selling Price (8500) and adding it to the SP, which results in $8500 + 1275 = 9775$. Loss must always be calculated on the Cost Price. ### Final Answer Therefore, the correct answer is **₹ 10000**.