Xavier Computer Limited Was Started in Early 2019 and Continued

Xavier Computer Limited was started in early 2019 and continued to operate until early 2022, when it was wound up due to disputes between the two principal shareholders. When it started, the company used the following accounting policies:
1. Use 50% declining-balance depreciation for the firm's only asset, a computer which cost $1,100,000 and has an estimated useful life of four years.
2. Estimate warranty expense as 10% of sales.
3. The year-end allowance for doubtful accounts should be 40% of gross accounts receivable.
Derive net income for 2019 to 2021. For the year-end balance for 2022, assume accounts receivable, allowance for doubtful accounts, and the warranty accrual are $0, as the firm wound itself up during the year and all timing differences have been resolved.
$$\begin{array} { | l | r | r | r | r | } \hline & 2019 & 2020 & 2021 & 2022 \\\hline \text { Sales (all on account) } & 3,400,000 & 3,600,000 & 4,100,000 & 410,000 \\\hline \begin{array} { l } \text { Warranties paid } \\\text { Proceeds on disposal of } \\\text { computer }\end{array} & 272,000 & 288,000 & 420,250 & 147,600 \\\hline \begin{array} { l } \text { Accounts receivable collected in } \\\text { the year }\end{array} & 2,958,000 & 2,880,000 & 3,895,000 & 1,126,000 \\\hline \begin{array} { l } \text { Accounts receivable written off } \\\text { in the year }\end{array} & 102,000 & 108,000 & 205,000 & 236,000 \\\hline \begin{array} { l } \text { All other expenses (paid in cash } \\\text { in the year incurred) }\end{array} & 2,380,000 & 2,520,000 & 2,767,500 & 287,000 \\\hline\end{array}$$