1. FHI has the opportunity to purchase the planes from Arland Manufacturing Company for $270 each. Arland maintains adequate inventories so that it can supply its customers with planes on demand. Should FHI accept the opportunity to outsource the making of its planes?

I understand that the relevant cost includes 3 unit-level costs, other manufac overhead, inventory cost, and leasing revenue of 48,000. But my question is that why we are using single 48,000 instead of 48,000 *4 remainig years.

Flying High Incorporated, (FHI) is a division of The Master Toy Company. FHI makes remote-controlled airplanes. During Year 5, FHI incurred the following costs in the process of making 6,800 planes. *The manufacturing equipment, which originally cost $340,000, has a book value of $272,000, a remaining useful life of four years and a zero salvage value. If the equipment is not used in the production process, it can be leased for $48,000 per year