Final answer:
The number of days for a buyer to cancel a purchase contract of a cooperative when the seller is not a developer depends on the jurisdiction and agreement conditions. The reference information does not provide a specific cancellation period; therefore, local real estate laws or professional consultation is advised.
Step-by-step explanation:
The question pertains to the number of days a buyer has to cancel a purchase contract of a cooperative when the seller is not a developer. The cancellation period for purchase contracts can significantly vary based on jurisdiction and the specific terms set forth in the contract itself.
The reference information discusses possession and the ability of either party to cancel and terminate the agreement under certain conditions, but it does not specify a standard cancellation period for a cooperative purchase by a non-developer seller. As a result, without specific information on local real estate laws, a standard cancellation period cannot be assumed, and one should refer to the purchase agreement or consult with a real estate attorney for clarity.