Brokerage In Case Of Redevelopment

In case of a redevelopment project in which a plot owner is collaborating with a developer, is the percentage commission charged by the broker as brokerage calculated on the entire property value as agreed upon when the agreement was signed, or the percentage of the property being sold by the plot owner to the developer. Say the value of the total property is X, and four builder floors are being built, two to be retained by the owner and two by the developer, with proportionate 50-50 share in the land, and the brokerage is Y%, so is the brokerage Y% of X, or Y% of 50% of X.