A man buys a chair and table for Rs. 6000. He sells the chair at a loss of 10% and the table at gain of 10%. He still gains Rs. 100 on the whole. Cost price of chair is:

Answer: Option A

If the CP of the chair be Rs. x then,
Total SP = $$\frac{\text{x}\times 90}{100}$$  + $$\left(\left(6000-\text{x}\right)\times \frac{110}{100}\right)$$
Or, 9x + 66000 - 11x = 61000
Or, 2x = 66000 - 61000 = 5000
Or, x = Rs. 2500