Civil Code, Art. 1539

The obligation to deliver the thing sold includes that of placing in the control of the vendee all that is mentioned in the contract, in conformity with the following rules: If the sale of real estate should be made with a statement of its area, at the rate of a certain price for a unit of measure or number, the vendor shall be obliged to deliver to the vendee, if the latter should demand it, all that may have been stated in the contract; but, should this be not possible, the vendee may choose between a proportional reduction of the price and the rescission of the contract, provided that, in the latter case, the lack in the area be not less than one-tenth of that stated. The same shall be done, even when the area is the same, if any part of the immovable is not of the quality specified in the contract. The rescission, in this case, shall only take place at the will of the vendee, when the inferior value of the thing sold exceeds one-tenth of the price agreed upon. Nevertheless, if the vendee would not have bought the immovable had he known of its smaller area of inferior quality, he may rescind the sale. (1469a)