An obligee may annul an onerous contract made by the obligor with a person who knew or should have known that the contract would cause or increase the obligor's insolvency. In that case, the person is entitled to recover what he gave in return only to the extent that it has inured to the benefit of the obligor's creditors.
An obligee may annul an onerous contract made by the obligor with a person who did not know that the contract would cause or increase the obligor's insolvency, but in that case that person is entitled to recover as much as he gave to the obligor. That lack of knowledge is presumed when that person has given at least four-fifths of the value of the thing obtained in return from the obligor.