How is the value of used appliances taken from the debtor calculated in exchange for an old debt whose original value has eroded?

The debt is calculated according to what the two parties agree upon. Either the goods are purchased from the debtor at a known price, and then a set-off occurs between the debt owed by him and this price, or there is a conciliation with compensation for all or part of the debt with these goods. This takes the ruling of a sale, involving the exchange of money for money, and the rulings of sale apply to it.