Hi, can you please help me solve these parts step by step with formulas. Thanks, I will give a rating!

***Please solve all parts for credit! Thanks, I appreciate it!

Problem: On January 1, 2020, Dewey Company purchased a mainframe computer for $150,000. The computer is estimated to have a $30,000 salvage value after its four year useful life. Fill in the appropriate amounts concerning the depreciation on the computer for the depreciation methods identified below. a) Straight Line Method: Depreciation Expense Book Value 12/31/2020 12/31/2021 12/31/2022 12/31/2023 b) Double-Declining Balance Method: Depreciation Expense Book Value 12/31/2020 12/31/2021 12/31/2022 12/31/2023