A merchant bought 140 cupboards at an auction. He sold 80 of them at a profit of Rs. 4,000 and the rest at a loss of Rs. 1,200. On the whole, he gained 10%. Then the cost of each cupboard is

Let the cost price of each cupboard be Rs $$x$$

Total cost price = $$140x$$

Selling price of first 80 cupboards = $$80x + 4,000$$

Selling price of the rest 60 cupboards = $$60x - 1,200$$

=> Total selling price of the cupboards = $$140x + 2,800$$

Also, he overall gained 10%, => Selling price = $$140x + \frac{10}{100} * 140x = 154x$$

=> $$154x = 140x + 2800$$

=> $$x = \frac{2800}{14} = 200$$

Thus, cost of each cupboard = Rs 200