Buyback Contract

Supplier A supplies Retailber B a product at $27/unit. Excluded from this wholesale price is the shipping cost of $1.00/unit which is incurred by Retailer B. Retailer Bs retail price is $54/unit. Supplier A's variable manufacturing cost is $15/unit. Retailer B plans to make a single purchase before the holiday season. Left over products are bought back by Supplier A. However, Retailer B must ship every unsold product back to Supplier A at a cost of $1.00/unit. If Supplier A can sell the leftover product to a discounter store for $20, what is the profit maximizing buyback price?