Use a signed result: revenue minus expenses is negative when expenses exceed revenue. That loss reduces equity. Owner contributions can offset a loss without turning them into revenue. Collecting an already recorded receivable exchanges one asset for another; it does not earn the same revenue twice. A balance sheet must still balance in a loss-making period.
Worked example
Separate example: revenue 50 minus expenses 65 = net loss 15, written -15 in the formula. Beginning equity 90 + contribution 10 + (-15) - withdrawal 5 = 80. Assets 105 = liabilities 25 + equity 80. A negative period result does not mean every asset balance is negative.
Badge Repair Studio / July 1-31 and July 31
All amounts are fictional dollars. July 1-31: completed services earned 90, rent used 60, supplies consumed 50, owner contribution 25 and owner withdrawal 5. Beginning equity was 200. July 31: Cash 95, Accounts Receivable 35, Equipment 100 and Loan Payable 30. These are final adjusted amounts; no other accounts, interest, taxes or depreciation apply. The 35 receivable is part of the 90 already earned. Use only these records, not personal finances.