Solution :
Correcting the errors by reversing the incorrect entry and then preparing the correct entry :
Sl. No. Description Debit Credit
1. Cash $600
Equipment $600
Salary and wages $600
Cash $600
2. Service revenue $450
Cash $450
Cash $4500
Account receivable $4500
3. Accounts payable $250
Equipment $250
Equipment $520
Accounts payable $520