Cost of machinery = Rs.2,52,000
Salvage value = Rs.12,000
Useful life = 6 years
Annual depreciation under straight line method will be:
Purchase Price of Machine Rs. 2,52,000 - Salvage value Rs. 12000 = Depreciable asset cost of Rs 2,40,000
6 year useful life = 1/6 depreciation rate per year
1/6 x 2,40,000 depreciable asset cost = Rs 40,000 annual depreciation