Andy Gibb, Morris Gibb and Robin Gibb oblige themselves jointly to deliver to John Lennon a particular horse on a certain date. The agreement among Andy Gibb, Morris Gibb and Robin Gibb which was made known to John Lennon, is that they will contribute the amount in buying the horse. The horse was not delivered on the due date because of the failure of Robin Gibb, to give his share of the purchase price. State the rights and obligations of the parties.