Where the evidence shows that defendant's contract to pay plaintiffs a certain commission for a sale of land, is either a joint contract with that of other owners of the land, or is an individual contract, the court properly refused to charge that defendant is only liable for his share of the commission to the extent of his individual interest; their liabilities can not be apportioned. Mosseau v. La Roche's Sons, 80 Ga. 568, 5 S. E. 780.