The way you do the journal entries for a sale transaction of Fixed Assets depends on the way you depriciate them. Let us assume you keep a "provision for depriciation" account for this purpose. Then follow the following guidelines.
1) Removing the cost of the assets sold from asset account
Sales of fixed assets account Dr xxx
Fixed Asset account Cr xxx
2) Removing the relevent depriciation amount (up to the date of selling - based on the accounting policy of the company) from "Provision for depriciation" account
Provision for depriciation account Dr xxx
Sale of Fixed assets account Cr xxx
Then balance the "Sale of Fixed assets" account and you will get the profit or loss of the transaction.
Tax implication of the transaction would certainly depend on the relevant tax jurisdiction of your country. Thus I can not answer with sure.
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