Answer:
the  depreciation expense using the double-declining-balance method for the years 2020 and 2021 is $18,000 and $10,800 respectively
Explanation:
The computation of the depreciation expense using the double declining method for the year 2020 and 2021 is as follows:
For 2020
= (Cost) Ă— depreciation rate
= $45,000 Ă— 1 Ă· 5 Ă— 2
= $18,000
For 2021
= ($45,000 - $18,000) Ă— 0.40
= $10,800
hence, the  depreciation expense using the double-declining-balance method for the years 2020 and 2021 is $18,000 and $10,800 respectively