Donegal footwear is an international supplier of outdoor footwear for adventurous families. currently, the company uses a logistical provider to provide warehouse services and handle packages destined for ground delivery. the contract calls for $9 million in annual fixed charges, which covers the provider's overhead and warehouse costs, and variable costs of $ 14.00 per package shipped. recently, donegal footwear found a warehouse it could lease at a cost of $15 million per year, which includes lease costs, labor, and management oversight. furthermore, the company found another provider who would deliver packages from the warehouse for $ 10.00 per package. considering only costs, how many packages must donegal footware ship to make the vertical integration into warehouse operations beneficial?