The value after 4 years will be $17,226.21. Here's how you find this answer.
First you divide 15 by 100 to get 0.15. 0.15 represents your percentage when you solve for depreciation.
Year 1: Now that you have you percentage in a decimal value, you take 0.15 and multiply it by $33,000. This will give you $4,950, which you subtract from $33,000. This gives you $28,050, which is the value of depreciation after the first year.
Year 2: To find depreciation after 2 years, you take the value from the year before ($28,050 in this case) and follow the same steps as you did to find year 1 depreciation. Take $28,050 and multiply it by 0.15 to get $4,207.5. Subtract $4,207.5 from $28,050 to get $23,842.50.
Year 3: Take $23,842.50 and multiply it by 0.15 to get $3,576.375. Now subtract $3,576.375 from $23,842.50 to get $20,266.125.
Year 4: Finally, take $20,266.125 and multiply it by 0.15 to get $3,039.91875. Subtract $3,039.91875 from $20,266.125 to get $17,226.20625. Round $17,226.20625 to the nearest tenths place to get a final answer of $17,226.21.
I hope this helps!