John Regan set up a garage and car sales business on 1 January 2024 with the following assets:

Land and Buildings: $120 000

Plant & Equipment: $60 000

Loose Tools: $5 000

Inventory of motor vehicles: $45 000

Inventory of car parts: $7 000

Cash at bank: $1 000

John decided on the following policy for depreciation 

1. Land, costing $70 000, is not to be depreciated.
2. Buildings, costing $50 000, are to be depreciated at 4% per annum on cost using the straight line method.
3. Plant and equipment is to be depreciated at 50% per annum using the diminishing balance method.
4. Loose tools are to be depreciated using the revaluation method.

Explain why John Regan does not depreciate each of the following:

(a) Land

(b) Inventory of motor vehicles 

Explain why John Regan uses the revaluation method to depreciate loose tools.