The trial balance for Windsor, Inc. appears as follows:


Windsor, Inc.
Trial Balance
December 31, 2017
Cash $230
Accounts Receivable 407
Prepaid Insurance 64
Supplies 140
Equipment 3120
Accumulated Depreciation, Equipment $470
Accounts Payable 300
Common Stock 940
Retained Earnings 1090
Service Revenue 2331
Salaries and Wages Expense 780
Rent Expense 390 0
$5131 $5131

If service for $137 had been performed but not billed, the adjusting entry to record this would include a: