The formula for calculating the double-declining-balance method is

a. book value at beginning of the year less residual value x 2 / estimated service life.

b. historical cost less residual value x 2/estimated service life.

c. historical cost x 1/service life.

d. book value at beginning of year x 2/estimated service life

d. book value at beginning of year x 2/estimated service life

Explanation:

Duble Declining method of depreciation is a method in which the depreciation is being charged at double rate than in the straight line depreciation method method do. It uses the double amount of carrying book value and estimated useful life. The depreciation charged at a faster rate.

Formula:

Depreciation = Book value of asset at the start of year x 2 / useful life