Filling out Form 593 California with multiple sellers what do I put in the selling price? is it just my portion? Also a question about cost basis

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Hi, the title pretty much asks the question. In section VI computation, do I put the sales price of the property or just my portion of it?  Also, for the cost basis, it was a trust deed that the borrower defaulted on. And the lenders in the trust deed got the property through a foreclosure. From my research, the cost basis is how much I put into the loan and the foreclosure fees. Is that correct? Chat GPT said that it could also be the FMV of the property when it was sold in the foreclosure. No one bid on the property obviously and it just went to the lenders. Thank you for any help given. It is really appreciated.

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The property in question is a piece of vacant land. Thank you.