Split-savings agreement
The seller’s revenue is lSALE x DP x T which is produced at a cost of lS x DP x T.
So the seller makes (lSALE - lS) x DP x T (seller’s benefit).
The buyer avoids paying lB x DP x T but pays the seller lSALE x DP x T in order to do so.
So the buyer saves (lB - lSALE) x DP x T (buyer’s benefit).