(b) On June 1, a customer paid $12,000 cash to Jack's Janitorial Company for services that are to be provided in equal amounts each month from June 1 to August 31. On June 1, Jack's Janitorial Company debited Cash and credited Accounts Receivable for $12,000. No journal entries have been made for this transaction since June 1. (Ouch! - that's wrong!) Fix the accounting records by showing the adjusting entry needed at June 30