An equipment purchase exchanges assets when paid in cash; it is not an immediate expense in this model. A service consumed now is an expense even if its bill is paid later: debit Expense and credit Accounts Payable. Paying that bill reduces the payable, not profit a second time. Before closing, list ending debit and credit balances once in a trial balance. Matching totals cannot detect every wrong account.
Worked example
Separate example: owner adds 70 cash, service earned on account is 18, collection is 6 and a current expense costs 4 cash. Debit balances: Cash 72, Receivable 12, Expense 4. Credit balances: Capital 70, Revenue 18. Each column totals 88. Profit = 18 - 4 = 14. Capital and revenue are both credits but mean different things.
Workshop records to review
Start with zero balances. U1: owner contributes 150 cash. U2: buy equipment for 40 cash, recorded as an asset. U3: finish a service and receive 30 cash immediately. U4: receive a bill for 12 of electricity consumed this period, due later. U5: pay 5 toward that bill. Use fictional dollars, accrual accounting and pre-closing balances. No other transactions, taxes, depreciation, fees or adjustments apply.